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The 10th International Conference on Quarks and Nuclear Physics will be hosted by the Institute of Cosmos Sciences of the University of Barcelona on 812 July, 2024. This conference follows the series of meetings previously held in Adelaide, Julich, Bloomington, Madrid, Beijing, Palaiseau, Valparaiso, Tsukuba and Tallahassee.
Experimentalists and theorists discuss recent developments in the field of hadron and nuclear physics, continuing previous discussions and presenting new results on the quark and gluon structure of hadrons, hadron spectroscopy and decays, hadron interactions and nuclear structure, and hot and cold dense matter.
Local Organising Committee (ICCUB)

This event is part of the grant CEX2019000918M funded by MCIN/AEI/10.13039/501100011033.
Amb el suport de l'Ajuntament de Barcelona – Districte de Les Corts
This event has received funding endorsement from IUPAP:
And from NuPECC:
Welcome to Barcelona
We analyze the modifications that a dense nuclear medium induces in the Ds(2317)± and Tcc(3875)±. In the vacuum, we consider them as isoscalar DK (Dbar Kbar) and DD (Dbar Dbar) Swave bound states, which are dynamically generated from effective interactions that lead to different Weinberg compositeness scenarios. Matter effects are incorporated through the twomeson loop functions, taking into account the self energies that the D, D, Dbar, Dbar, K and Kbar develop when embedded in a nuclear medium. Although Ds(2317) and Tcc(3875) particleantiparticle lineshapes are the same in vacuum, we find extremely different density patterns in matter. This chargeconjugation asymmetry for the Ds(2317) [Tcc[3875]) mainly stems from the very different kaon [Dbar and Dbar] and antikaon [D and D] interaction with the nucleons of the dense medium. We show that the inmedium lineshapes found for these resonances strongly depend on their DK and DD molecular contents, respectively, and discuss how this novel feature can be used to better determine/constrain the inner structure of these exotic states.
See the attached file.
I will discuss recent advances on the description of leptonnucleus interactions in the energy region relevant for oscillation experiments. Various methods employing Quantum Monte Carlo techniques have been employed to derive the presented results.
The Facility for Antiproton and Ion Research (FAIR) in Darmstadt, which is being built close to GSI Helmholtzzentrum Darmstadt, makes significant progress in its mission to provide unique opportunities for a rich and multidisciplinary research program. The mission of FAIR comprises the investigation of QCDMatter and QCDPhase Diagram at highest baryon density; nuclear structure and nuclear astrophysics investigations with nuclei far off stability; QCD studies with cooled, highintensity antiproton beam; precision studies on fundamental interactions and symmetries; high density plasma physics; atomic and material science studies; radiobiological investigations and other application oriented studies.
The accelerator complex of FAIR will provide high intensity beams of protons, (radioactive) ions and finally antiprotons. The heart of the FAIR facility is the SIS100 synchrotron, which is currently being installed in a tunnel with a circumference of 1.1 km. The fragment separator SuperFRS will be provide high intensity, high energy exotic beams for the study of nuclei far off stability employing inflight fragmentation and subsequent identification of the produced radioactive nuclei.
FAIR is realized in steps: Early Science will make use of beams from the GSI synchrotron SIS18 and the SuperFRS; First Science includes operation of the SIS100 synchrotron and will provide excellent research opportunities for the investigation of structure and reactions of exotic nuclei. In the next step, intense highenergy beams will be made available for the study of QCD matter at highest baryon densities. Research facilities for atomic physics, plasma physics, materials and biophysics research are completed afterwards provided sufficient funding will be made available by the international FAIR shareholders. The final goal is the building of a HighEnergy Storage Ring for antiprotons and exotic ions (HESR), which will offer novel research possibilities for hadron, nuclear and atomic physics.
Researchers from over 50 countries are actively involved in experiments at FAIR, contributing to the development and construction of large variety of different detectors. The FAIR Phase0 program at the GSI accelerator facilities offers excellent opportunities to test detectors and concepts developed for FAIR and a staged approach to FAIR science and smooth transition from GSI to FAIR operation.
In the talk, the status and the perspectives for science at FAIR will be discussed and the current planning for the commissioning phase of FAIR will be presented.
Nucleon elastic form factors encode crucial information about its charge and
magnetization distributions. For many decades, nucleon form factors were studied by
using unpolarized electronnucleon cross section measurements. The advent of electron
beams with higher luminosities and beam polarization coupled with large acceptance
detectors, polarized targets and recoil polarimeters enabled a wealth of information on
nucleon form factors over a broad range of momentum transfer (Q^2). While plenty of
information is available on the proton, no data above Q^2 = 3.5 GeV^2 is available on the
neutron electric form factor. Pushing the data to a higher Q^2 allows constraining spin
flip GPDs and serves as a bench mark for various theoretical models. Using quasielastic
scattering of a polarized electron beam on a polarized ^3He target, one can extract the
GEn term which is proportional to the measured asymmetry from opposite electron
beam helicity.
The GEnII experiment at Jefferson lab utilizes a polarized He3 target for a high Q^2
measurement of the neutron electric form factor. The target consists of a pumping
chamber (where polarization of He3 takes place), a target chamber (where e beam
interacts with the target material) and transfer tubes (which facilitate a convective flow
of the polarized material). ^3He gas at ~8 atm pressure is filled into the glass cells along
with RbK alkali mixture and narrow band diode lasers are used for polarizing the He3
using a SEOP (Spin Exchange Optical Pumping) technique. The target system used in
the experiment includes multiple Helmholtz coils to create a holding field that
determines the direction of polarization for the ^3He nuclei. Two polarimetry techniques
are used to determine the absolute (EPR) and relative (EPR) polarization during
production running. The GEnII experiment finished taking data at three out of four
kinematic settings and is scheduled for completion in the Fall of this year. Overall target
performance and other instrumentation used in the GEnII experiment (GEMs,
calorimeters and hodoscopes) will be briefly discussed in this talk.
The ALICE experiment, optimized to study nuclei collisions at the ultrarelativistic energies provided by the LHC, is approaching to a new upgrade phase, foreseen in 2026 during the third Long Shutdown of the accelerator. This upgrade includes the replacement of the 3 innermost layers of the Inner Tracking System, the detector closest to the interaction point, which is currently made of 7 layers of Monolithic Active Pixels (MAPS).
The main features of this new vertex detector, named ITS3, are the extremely low material budget (only 0.07% X0 per layer) and the reduced radial distance of 19 mm to the interaction point. To achieve this goal, the ITS3 will be made of waferscale monolithic pixel sensors, thinned down to 50 um and curved in order to ensure a true cylindrical geometry, without any flexible printed circuits in the active area. The mechanical support and the cooling system will be optimized to reduce the total material budget: the layers will be kept in place thanks to ultralight carbon foam support elements, and they will be cooled through a lowspeed air flow.
The success of the project depends on many interconnected aspects and an intense R&D activity is ongoing to investigate all these components, from the development of the sensor to the mechanics, cooling and integration. This contribution summarizes the status of the project and presents selected results from the characterisation of the first prototype chips.
ePIC will be a generalpurpose detector designed to enalbe the entire physics program of the ElectronIon Collider (EIC) at BNL, USA. Several key physics measurements depend on efficient Particle Identification (PID). The PID system of ePIC covers a wide pseudorapidity (3.3<η<3.5) and momentum range. Several technologies have been identified to serve such purpose.
In the forward region (1.5<η<3.5) a Dual Ring Imaging Cerenkov detector (dRICH) will be employed to provide efficient and continuous hadron PID from 1 GeV/c to 50 GeV/c and to support the electromagnetic calorimeter by pion rejection in the lower momentum region. The dRICH comprises two different radiators, aerogel and gas (C2F6), to cover the entire momentum range. SiPM based photosensors are placed in six spherical sectors to detect Cherenkov photons which are focused by six spherical mirrors.
The presentation will introduce the dRICH detector and discuss several results from simulation studies, with a special focus on the separation power for pions and kaons and its depencency with the particle momentum and pseudorapidity.
R&D efforts are ongoing to develop the Cylindrical Micromegas Barrel Layer (CyMBaL) for the central region of the ePIC detector, the first experiment at the future Electron Ion Collider (EIC).
The Micromegas detectors will be a part of a multitechnology tracker that needs to fit inside a 1.7 T solenoid, bringing stringent constraints on space. Additionally, a low material budget is necessary to not degrade the measurements of the detectors behind. As such, a light resistive Micromegas equipped with a 2D readout is required. The goal is to optimise the readout system to limit the number of channels while keeping a spatial resolution of about 150µm.
I will present the current status of the R&D and the results from the first prototypes tested.
Heavyflavor hadrons with nonconventional properties have been observed
over the past two decades. Some of these states have both quarkonium and
exotic interpretations, while several other states exhibit a distinct
exotic internal structure, including charged, openflavor, double
heavyflavor, and full heavyflavor states. Interpretations of these
states vary, ranging from tightlybound compact multiquark objects to
looselybound hadronic molecules. The searches for new exotic candidates
provide not only insights on the quark binding mechanisms within hadrons
but also offers valuable inputs for a better understanding of the
nonperturbative regime of QCD. In this context, the LHCb experiment,
dedicated to studying heavyflavor hadrons using hadron collision data
from the LHC operation, plays a crucial role as demonstrated by the
large number of new states observed. In this presentation, the latest
results from LHCb regarding exotic hadron spectroscopy are shown.
The nature of the three narrow pentaquark states observed by the LHCb in 2019 remains a puzzle to the hadron physics community. While the hadronic molecule picture is favored by most analyses due to their proximity to twohadron thresholds, a compact or even virtual state interpretation have yet to be completely ruled out. In addition, a purelykinematic rescattering mechanism involving a triangle loop has been suggested as a possible origin for enhancements in the invariant mass, where the signal does not correspond to any unstable quantum state. Although this interpretation was shown to be unlikely for the $P_\psi^N(4312)^+$ and $P_c(4440)^+$ states due to lack of proper hadronrescattering thresholds, it is still a plausible explanation for the $P_c(4457)^+$, requiring further amplitude analysis. In our study, we solve this general classification problem via machine learning, which works as a valuable tool in identifying the nature of enhancements. We develop, for the first time, a deep neural network (DNN) capable of distinguishing triangle singularity from polebased amplitudes. After applying the trained DNN on the $P_\psi^N(4312)^+$ state, we reach a conclusion consistent with previous analysis that a polebased interpretation is favored, and the triangle singularity may be ruled out for this signal. Similar DNN models are developed to classify the other two states. Finally, using our modelselection framework, we attempt to provide an interpretation for the $P_c(4457)^+$ state.
Keywords: pentaquark, triangle singularity, machine learning
Inverse problems, in particular those related to obtaining the scattering amplitudes from experimental data, are known to be hard, both conceptually and numerically. Recently, JPAC collaboration has developed a Deep Neural Network based approach that allows to address essential parts of this problem. We showed that a neural network trained with synthetic differential intensities calculated with scattering length approximated amplitudes, accurately predicts the Riemann sheet of the pole which is closest to the physical region. Specifically, for the $P_c(4312)$ signal, the neural network classifier provides the virtual state related to the pole on the 4th Riemann sheet as a most probable interpretation. We also discuss the adjustments necessary for the method to be applicable to lighter resonances.
Physicists have been captivated by the spectrum of hadrons for decades, seeking to better comprehend the fundamental building blocks of matter. While various experiments have laid the foundation for this spectrum, Lattice Quantum Chromodynamics (Lattice QCD) has revealed new states with forbidden $J^{PC}$ values. This has challenged the constituent quark model, suggesting exotic hybrid mesons that could reshape our understanding of hadronic structure and quarkgluon interactions through gluonic excitations.
The GlueX experiment at Jefferson Lab plays a pivotal role in this quest, with its efforts centered on analyzing photoproduction data. In order to investigate the lightest predicted exotic state with $J^{PC}=1^{+}$, known as the $\pi_1$ meson, significant attention has been directed towards both $\eta\pi^{0}$ and $\eta' \pi^{0}$ systems.
Detailed ongoing amplitude analysis studies of $\gamma p \rightarrow \eta^{(}{'^{)}}\pi^{0} p \rightarrow 4\gamma \pi^+ \pi^ p$, leveraging the polarization of the photon beam at the GlueX experiment, will be discussed. Specifically, the extracted moments of angular distributions for these channels will be presented, along with the differential crosssection results for the $a_2(1320)$ meson. These findings aid in identifying the dominant production mechanism and offer valuable insights into complex hadronic interactions. Ultimately, this will contribute to the ongoing search for and future identification of exotic hybrid meson candidates.
The pole structure of $P_\psi^N(4312)$ pentaquark charm remains elusive, with various models attempting to explain the experimental data from LHCb run $2$ [1,2]. The current impasse persists until we acquire additional data with improved resolution or secure a definitive explanation. Notably, the application of machine learning in understanding resonances has garnered attention [38]. Its appeal lies in the vast parameters offered by neural networks and their ability to generalize beyond the training dataset. Training them with a minimallybiased dataset can offer insights that can be used as a guide for model selection or theory building. This study extends our prior investigation [9,10], where we employed machine learning to examine the pole structure of $P_\psi^N(4312)^+$. In our prior work, we generated our training dataset exclusively within the $[4412, 4412]$ MeV energy range, simulating background signals with a quadratic polynomial function. In this work, we explore whether expanding the region of interest and introducing background noise derived from the poles of the $S$matrix itself can lead our neural network to discriminate differently. The outcomes of this research aim to validate our initial findings and shed light on the impact of background poles on our probing, at least within the context of machine learning.
References:
[1] R. Aaij et al. (LHCb Collaboration), Phys. Rev. Lett. 122, 222001 (2019).
[2] LHCb Collaboration, “Observation of a narrow pentaquark state, Pc(4312)+, and of twopeak structure of the Pc(4450)+,” HEPData (collection) (2019), https://doi.org/10.17182/hepdata.89271.
[3] D. L. B. Sombillo, Y. Ikeda, T. Sato, and A. Hosaka, Phys. Rev. D 102, 016024 (2020).
[4] D. L. B. Sombillo, Y. Ikeda, T. Sato, and A. Hosaka, FewBody Systems 62, 52 (2021).
[5] D. L. B. Sombillo, Y. Ikeda, T. Sato, and A. Hosaka, Phys. Rev. D 104, 036001 (2021).
[6] L. Ng, L. Bibrzycki, J. Nys, C. Fern ́andezRam ́ırez, A. Pilloni, V. Mathieu, A. J. Rasmusson, and A. P. Szczepaniak (Joint Physics Analysis Center), Phys. Rev. D 105, L091501 (2022).
[7] J. Liu, Z. Zhang, J. Hu, and Q. Wang, Phys. Rev. D 105, 076013 (2022).
[8] Z. Zhang, J. Liu, J. Hu, Q. Wang, and U.G. Meißner, Science Bulletin 68, 981 (2023).
[9] L. M. Santos and D. L. B. Sombillo, Phys. Rev. C 108, 045204 (2023).
[10] L. M. Santos, V. A. A. Chavez, and D. L. B. Sombillo, “Pole structure of pN
ψ (4312)+ via machine learning,” (N.D.), unpublished.
Neutron star merger events are unique laboratories for exploring matter under extreme temperatures and densities. These conditions might harbor exotic particles like hyperons. In this talk I will discuss how the presence of hyperons influences the properties of matter (equation of state) and how this manifests in observable phenomena. The main focus will be on the distinct signatures arising from the thermal behavior of hyperons. Their presence leads to a significant decrease in thermal pressure, resulting in a characteristic increase of up to 150 Hz in the dominant frequency of gravitational waves emitted after the merger, compared to scenarios where hyperons are not present in matter. This effect opens a potential avenue to probe the composition of dense matter in neutron stars using future gravitational wave observations.
The cores of neutron stars (NS) reach densities several times the nuclear saturation density and could contain strangeness containing exotic particles such as hyperons. During the binary inspiral, viscous processes inside the NS matter can damp out the tidal energy induced by the companion and convert this to thermal energy to heat up the star. We demonstrate that the bulk viscosity originating from the nonleptonic weak interactions involving hyperons is several orders of magnitude higher than the standard neutron matter shear viscosity in the relevant temperature range of $10^610^9$K and for heavier mass NSs ($M \geq 1.6M_{\odot}$) that contain a significant fraction of hyperons in their core, the bulk viscosity can heat up the stars upto $0.1  1$ MeV before the final merger. This ``tidal heating" process also introduces a net phase shift of $10^{3}0.5$ rad, depending on the component mass, in the gravitational wave (GW) signal that can potentially be detected using current and future generation GW detectors. Such a detection would be the direct confirmation of the presence of hyperons inside the NS core, having a great significance for the study of dense matter under extreme condition.
We show that results for the thermodynamics of strongly interacting matter obtained by state of the art MonteCarlo simulations of lattice QCD can be adequately described within a generalized BethUhlenbeck type approach, where the hadron resonance gas (HRG) phase appears as a statistical ensemble of multiquark clusters. The underlying chiral quark dynamics is coupled to a background gluon field using the Polyakov gauge. The transition to the quarkgluon plasma (QGP) phase appears as a Mott dissociation of the quark clusters described by mediumdependent hadron phase shifts that encode the dissociation of bound states in the continuum of scattering states as triggered by the chiral symmetry restoration transition. An important ingredient are Polyakovloop generalized distribution functions of multiquark clusters which are derived here for the first time [1].
This new approach gives a quantitative understanding for the observation of ultrarelativistic heavyion collision experiments that the abundances of hadrons produced in these collisions are well described by a statistical model within a sudden chemical freezeout at a welldefined hadronization temperature despite the fact that the melting of the chiral condensate proceeds as a smooth crossover.
We report for the first time the remarkable finding that the ratio of generalized baryon number susceptibilities $R_{42}^B(T)=\chi_4^B (T)/\chi_2^B (T)$, which interpolates between the value $R_{42}^B(T\simeq 140~{\rm MeV})=1$ for a pure HRG and $R_{42}^B(T>250~ {\rm MeV}) \sim 2/(3\pi^2) $ for the QGP shall not be mistaken for a measure of the fraction of hadrons in the system. Its deviation from unity below the chiral restoration temperature can actually quantify the degree of overlap of quark wave functions which leads to the quark Pauli blocking effect in the HRG resulting in repulsive residual interactions which we model by a temperature dependent excluded baryon volume, in accordance with lattice QCD.
[1] D. Blaschke, M. Cierniak, O. Ivanytskyi and G. Röpke, Eur. Phys. J. A 60 (2024)
[2] D. Blaschke, O. Ivanytskyi and G. Röpke, in preparation
We propose a scenario where the existence of a scalar, electrically neutral flavorsinglet threediquark bound state, the light sexaquark S(uuddss), with a mass well below the doubleΛ threshold M_{ΛΛ} = 2231.4 MeV entails the gravitational instability of lowmass neutron stars due to its BoseEinstein condensation (BEC) [1]. Since in this state the neutron star core loses the pressure support against gravity, the resulting density pileup inevitably triggers the Mott dissociation of the S into its diquark constituents which in turn form a Bardeen–Cooper–Schrieffer (BCS) type BEC state of diquark Cooper pairs in the color superconducting colorflavorlocking (CFL) phase. Within this scenario the deconfinement of the CFL quark matter is a special kind of BECBCS transition and its onset density is controlled by the sexaquark mass. Remarkably, the most uptodate results on the sexaquark mass assume an early deconfinement of SQM in NS with masses about 1 M_sun. Furthermore, we discuss the phenomenological consequences of the presence of the CFL SQM in NS [2]. We analyze the present observational and multimessenger data in order to constrain the parameters of the CFL quark matter. This analysis independently leads to the conclusion about an early onset of SQM and assumes all the medium mass NS with masses M=1 – 1.4 M_solar to have a quark core. We also demonstrate that such an early deconfinement scenario naturally explains the nature of the recently observed enigmatic HESS J1731347 compact object [3]. Another intriguing consequence of the CFL colorsuperconductivity corresponds to the possibility of absolutely stable of SQM. We investigate the parameter space of SQM, which is consistent with the present observational and multimessenger constraints and simultaneously provides its absolute stability. Finally, given the fact that the performed study is based on a chiral model of SQM with nonlocal interaction, which by construction exhibits an asymptotically conformal behavior, we consider the question of approximately conformal quark matter in NS and demonstrate that it is an unlikely scenario. Instead, we argue that a pronounced peak of squared speed of sound reaching about 0.6 corresponds to the quark boundary of quarkhadron mixed phase.
[1] D. Blaschke, O. Ivanytskyi, M. Shahrbaf, Quark deconfinement in compact stars through sexaquark condensation, Contribution to the Book "New Phenomena and New States of Matter in the Universe. From Quarks to Cosmos" edited by C. A. Z. Vasconcellos, P. O. Hess and T. Boller, World Scientific (2023), pp. 317342.
[2] David Blaschke, Udita Shukla, Oleksii Ivanytskyi, Simon Liebing, Phys. Rev. D 107, 6, 063034 (2023).
[3] Violetta Sagun, Edoardo Giangrandi, Tim Dietrich, Oleksii Ivanytskyi, Rodrigo Negreiros, Constança Providencia, Astrophys. J. 958, 1, 49, (2023)
We propose a modification to the relativistic meanfield $\sigma\omega$ model by incorporating the Pauliblocking effect arising from quark exchange interactions between baryons. In dense baryonic matter, where nucleon wave functions exhibit finite overlap, the quark exchange effects governed by the Pauli principle become significant at high densities. A quantitative estimate for this process has been made within a harmonic oscillator confinement potential model for the nucleons as threequark bound states. The resulting contribution is employed here as an additional Pauliblocking shift to the baryon selfenergy. Our analysis reveals that incorporating quark exchange contributions leads to an increase in the energy per baryon, resulting in a stiffening of dense baryonic matter. Furthermore, we find that the contribution from isovector meson exchange may be negligible, primarily due to the isospin asymmetry dependence of the quark exchange effect.
Recent applications of the subtracted second randomphase approximation (SSRPA), based on Skyrme functionals, to the study of GamowTeller excitations and betadecay will be presented. The comparison with the conventional randomphase approximation (RPA) results and experimental data is also discussed. It is found that, the amount of GamowTeller strength obtained in SSRPA is much lower than the RPA one, and it agrees better with experimental data [1,2]. The inclusion of twoparticletwohole configurations is responsible for this quenching, avoiding thus the use of any “adhoc” quenching factors normally adopted in this kind of studies. The betadecay half lives are also calculated and discussed, showing that also in this case the inclusion of the woparticletwohole configurations allows for a better description of the experimental values [1,3]. This result may have implications for the computation of nuclear matrix elements in the same framework for neutrinoless doublebeta decay.
References
[1] D. Gambacurta, M. Grasso, and J. Engel Phys. Rev. Lett. 125, 212501, (2020)
[2] D. Gambacurta and M. Grasso, Phys. Rev. C 105, 014321, (2022)
[3] D. Gambacurta and M. Grasso, in preparation
Neutrinoless doublebeta decay ($0\nu\beta\beta$)is a transition in nuclei where two neutrons simultaneously transform into two protons, accompanied by the emission of only two electrons [1]. This secondorder process, if observed, would proof that neutrinos are Majorana particles (their own antiparticles), shed light on the existence of massive neutrinos and explain the predominance of matter over antimatter in the universe.
The halflives depend on their square of a nuclear matrix element (NME) which has to be calculated due to the fact that $0\nu\beta\beta$ has not been measured yet.
In this talk we will discuss computations of the NMEs at the N2LO order (nexttonext leading order)[2] corrections within the nuclear shell model framework. These calculations aim to reduce the uncertainty surrounding the NMEs ($\mathcal{M}^{0\nu\beta\beta}$). First we will present the contribution of ultrasoft (low momentum) neutrinos which can be dominant in some scenarios involving light sterile neutrinos[3]. Then we will present novel results for the full N2LO NMEs, which have not been computed yet in the literature.
Finally, we study secondorder electromagnetic doublemagnetic dipole ($M1M1$) due to the connection between $M1M1$ and $0\nu\beta\beta$ NMEs [4]. We compute the nuclear matrix elements for the following nucleus: $^{20}$Ne, $^{48}$Ti, $^{40}$Ca and $^{72}$Ge in the nuclear shell model framework with different valence spaces and interactions. We estimate the quality of the results by comparing related calculations with data of firstorder electromagnetic transitions and energy spectra and to recent doublegamma decay experiments [5].
[1] M. Agostini et al. Rev. Mod. Phys. 95, 025002 (2023)
[2] L. Jokiniemi, D. Castillo, P. Soriano, J. Menéndez, in progress.
[3] W. Dekens et al, arXiv.2402.07993.
[4] B. Romeo, J. Menéndez, C. Peña Garay. Phys. Lett. B 827, 136965 (2022).
[5] D. FreireFernández et al,arXiv:2312.11313.
$2\nu \beta \beta$ decay to excited states of heavy nuclei
In doublebeta decay, two neutrons convert into two protons, accompanied by the emission of two electrons. According to the Standard Model (SM), this decay, called twoneutrino double$\beta$ decay ($2\nu \beta \beta$ decay), involves the emission of two antineutrinos, maintaining an equilibrium between matter and antimatter and preserving the principle of conserving lepton number. In models beyond the SM, this reaction is allowed without the emission of any neutrino. The neutrinoless decay, violates leptonnumber conservation of the SM and creates matter ($2e^{}$) but no antimatter ($0\overline{\nu}$) [1].
The empirical observation of such reactions would signify the confirmation of physics beyond the SM. The exploration of $0 \nu \beta \beta$ decay serves as a driving force behind our investigation into the $2 \nu \beta \beta$ decay. The initial and final nuclear states are common in both scenarios. Therefore, the methodologies applied in the investigation of $2 \nu \beta \beta$decay matrix elements are also applicable to the neutrinoless case.
In this study, we investigate the twoneutrino doublebeta decay ($2\nu\beta\beta$) of $^{76}$Ge, $^{82}$Se, $^{130}$Te to the first excited $0^{+}_2$ state of $^{76}$Se, $^{82}$Kr, $^{130}$Xe within the framework of the nuclear shell model [2]. This method describes well the $2\nu\beta\beta$ decay to the ground state of these nuclei [3,4]. We consider different interactions and we analyze the validity of these interactions in reproducing the experimental properties of the initial and final states of the decay. Subsequently, we calculate the matrix elements for the $2 \nu \beta \beta$ decay. We compare our results with the predictions of other manybody methods and with the latest experimental limits.
Referencias
[1] M. Agostini, G. Benato, J. A. Detwiler, J. Men\'endez, F. Vissani. Rev. Mod. Phys. 95: 025002 (2023).
[2] B. Benavente, D. Frycz, J. Men\'endez, in preparation.
[3]E. Caurier, F. Nowacki, A. Poves. Phys. Lett. B 711: 1, 6264 (2012).
[4] A. Barabash. Universe. 6(10): 159 (2020).
Precision spectrum shape measurements in nuclear beta decay can be used for testing the Standard Model and physics beyond it with accuracy being competitive with highenergy collider experiments. Such a comparison can be carried out in the framework of effective field theory. The most prominent and poorly known effect in the Standard Model is weak magnetism [1], the higherorder recoil correction induced by nuclear pion exchange. Knowledge of this factor allows for study of the QCD influence on beta decay and plays an important role in determining the significance of the reactor neutrino anomaly. Searches for physics beyond the Standard Model can be realized by exploring the Fierz interference term, also modifying the beta spectrum shape.
We performed precision measurements of the beta spectrum shapes for the pure GamowTeller decays of $^{114}$In and $^{32}$P. The measurements were carried out using the miniBETA spectrometer, which is a combination of a plastic scintillation energy detector and a thin gas detector for the tracking of low energy electrons.
In the talk, the motivation, principle of the measurement and the first weak magnetism and Fierz term extractions from the spectrum shape of the $^{114}$In to $^{114}$Sn transition [2] will be discussed. The preliminary result obtained from the $^{32}$P to $^{32}$S transition will be presented as well.
References:
1. N. Severijns, L. Hayen, V. De Leebeeck, S. Vanlangendonck, K. Bodek, D. Rozpedzik, and I. S. Towner, Physical Review C 107, 015502 (2023).
2. L. De Keukeleere, D. Rozpedzik, N. Severijns, K. Bodek, L. Hayen, K. Lojek, M. Perkowski, and S. Vanlangendonck, arXiv:2404.03140 [nuclex] (2024).
Precision measurements involving nuclei are at the cutting edges of nuclear physics and testing the Standard Model (SM) of physics. For instance, precision beta decay measurments have the potential to constrain beyond SM physics at TeV scales. To interpret these experiments, it is crucial to have comparably accurate theoretical predictions of relevant quantities along with an accurate understanding of the underlying nuclear dynamics. In this contribution, I will overview recent calculations of electroweak processes with quantum Monte Carlo (QMC) computational methods used to solve the manybody Schrödinger equation. The QMC approach retains the complexity of manynucleon dynamics and provides highly accurate results for light nuclei. I will discuss calculations of observable quantities with readily available datasuch as beta decay, muon capture, and electromagnetic reactionsused to validate models of nuclear manybody interactions and electroweak currents. I will then present QMC calculations of the $^6{\rm He}$ beta decay spectrum and show that the estimated theoretical uncertainties are comparable to the experimental precision, thus allowing for further constrains of new physics at TeV scales.
The JPET [1, 2, 3] is a highacceptance multipurpose detector optimized
for the detection of photons from positronelectron annihilation and can be used
in a broad scope of interdisciplinary investigation, e.g. medical imaging, fun
damental symmetry tests, and quantum entanglement studies, etc. For this
purpose, the Positronium system, which consists of a bound state of an electron
and a positron, is used in experiments where we can test the predictions of quan
tum electrodynamics (QED). In particular, we look for new physics studying
the Ps triple state, the orthopositronium (oPs), which mainly decays to three
photons.
We look for the socalled Alice or Mirror Matter (MM), a new type of matter
and a suitable candidate for Dark Matter, performing a highprecision measure
ment of the lifetime of the oPs state, to achieve the needed accuracy for testing
the present QED calculations. A discrepancy with the expectation from theory
could indicate the presence of Physics Beyond the SM, i.e. a signal for MM. In
addition, profiting from the triggerless acquisition mode of the JPET detector,
we are searching for decays of the oPs into 4γ and 5γ, the former Cviolating
decay and the latter never observed. Present limits in these forbidden and
rare decays can be improved thanks to the large acceptance and high angular
resolution of the JPET detector.
References
[1] P. Moskal et al. In: Science Advances 7 (2021), eabh4394.
[2] P. Moskal et al. In: Nature Communications 12 (2021), p. 5658.
[3] P. Moskal et al. In: Nature Communications 15 (2024), p. 78.
The search for new particles in the low mass range is motivated by new hidden sector models and dark matter candidates introduced to account for a variety of experimental and observational puzzles: the smallscale structure puzzle in cosmological simulations, anomalies such as the 4.2σ disagreement between experiments and the standard model prediction for the muon anomalous magnetic moment, and the excess of e+e− pairs from the 8Be and 4He nuclear transitions to their ground states observed by the ATOMKI group. In these models, the 1−100 MeV mass range is particularly wellmotivated, and the lower part of this range still remains unexplored. The PRad collaboration at JLab developed an experimental proposal to search for these particles by direct detection of all three final state particles in the electroproduction experiment allowing for an effective control of the background. It will cover the 3  60 MeV mass range, focusing on the detection of hypothetical X17 particle. This experiment was fully approved by the recent JLab’s PAC50 with a highest “A” scientific rating. Currently the collaboration is preparing this experiment to be performed as early as next year. The status of this experiment will be presented and discussed in this talk.
The Positron Working Group at Jefferson Lab is designing a positron source, transport beamlines, and experiments for an exciting physics program to begin in the mid2030’s. Some topics which will play important roles include Deeply Virtual Compton Scattering as a probe of GPDs, improving our understanding of the nucleon EM form factors, precision studies of 2photon exchange, and searches for dark matter.
Previous searches for a dark photon have usually required its onshell production, and published results have reached high sensitivity. However, a significant region of phase space remains unexcluded in the JLab energy regime which will require new experiments effectively having several orders of magnitude higher Figure of Merit. Searching for amplitudelevel signals is the approach I discuss here. This also avoids the interpretational ambiguity arising in many experiments from the unknown details of a potential dark photon decay.
In Bhabha scattering, e+e > e+e, the virtual exchange of a dark boson would interfere with photon exchange to produce changes in the yield and polarizedbeam asymmetries. These effects would be relatively large in the schannel near resonance. I will present exploratory calculations of several observables which appear most useful for amplitudebased dark photon searches in the mass range of approximately 10100 MeV/c2.
Investigating the potential feeble interaction between particles in the Standard Model (SM) and the Dark Sector (DS) is a significant frontier in particle physics. One possible manifestation of this feeble interaction is the dark photon, theorized as a vector gauge mediator that interacts very weakly with SM fermions.
The BGOOD photoproduction experiment combines a central electromagnetic calorimeter with a forward spectrometer for charged particle detection. This configuration enables the complete detection of reaction final states such as $\pi^0 p$, $\eta p$, and $2\pi^0 p$. These are wellsuited channels for the study of the mass resolution with regard to the dark photon search. The missing mass of the photons from $\eta$ decay were used to determine the mass resolution of the detector. Kinematic fitting techniques are also used to enhance the mass resolution, a critical element for accurate particle identification in highenergy experiments.
Supported by DFG projects 388979758/405882627 and the European Union’s Horizon 2020 programme, grant 824093.
The fundamental QCD symmetries at low energies and the new physics Beyond the Standard Model (BSM) are two frontiers in the contemporary physics. The Primakoff effect, a process of highenergy photo or electroproduction of mesons in the Coulomb field of a target offers a powerful experimental tool to explore both fundamental issues. A comprehensive Primakoff experimental program has been developed at Jefferson Laboratory (JLab) to perform precision measurements of the twophoton decay widths and the transition form factors of $\pi^0$, η and ηꞌ and to search for dark scalars or pseudoscalars via the Primakoff effect. A measurement of the $\pi^0\rightarrow\gamma\gamma$ radiative decay width was carried out at JLab 6 GeV and the published result achieved a precision of 1.5%. The data collection for the η radiative decay width measurement at JLab 12 GeV was completed in 2022 and data analysis is in progress. The future JLab 22 GeV upgrade will offer a new opportunity to perform the Primakoff experiments off an atomicelectron target with experimental sensitivities not previously achievable. The status of this program and its physics impact will be presented.
We analyse recent lattice data for the gravitational form factor of the pion within the framework of known theoretical information such as Chiral Perturbation Theory, Large Nc and perturbative QCD.
The internal structure of all lowestlying pseudoscalar mesons with heavylight quark content is studied in detail using an algebraic model that has been applied recently, and successfully, to the same physical observables of pseudoscalar and vector mesons with hiddenflavor quark content, from light to heavy quark sectors. The algebraic model consists on constructing simple and evidencebased ans¨atze of the meson’s BetheSalpeter amplitude (BSA) and quark’s propagator in such a way that the BetheSalpeter wave function (BSWF) can then be readily computed algebraically. Its subsequent projection onto the light front yields the light front wave function (LFWF) whose form allows us a simple access to the valencequark Parton Distribution Amplitude (PDA) by integrating over the transverse momentum squared. We exploit our current knowledge of the PDAs of lowestlying pseudoscalar heavylight mesons to compute their Generalized Parton Distributions (GPDs) through the overlap representation of LFWFs. From these three dimensional knowledge, different limits/projections lead us to deduce the related Parton Distribution functions (PDFs), Electromagnetic Form Factors (EFFs), and Impact parameter space GPDs (IPSGPDs). When possible, we make explicit comparisons with available experimental results and earlier theoretical
predictions
The world’s largest sample of J/ψ events accumulated at the BESIII detector offers a unique opportunity to investigate η and η′ physics via two body J/ψ radiative or hadronic decays. In recent years the BESIII experiment has made significant progresses in η/η′ decays. A selection of recent highlights on the transition form factor measurements of η/η′ at BESIII are reviewed in this report.
In this talk I will present the main predictions of the holographic graviton softwall model (GSW). In particular, I will discuss the properties of mesons, glueballs and, recently, hybrids. This model relies on a semiclassic approximation of non perturbative QCD. Within this approach, QCD fields are described via their duals propagating in a modified space, with respect to the usual AdS5. For glueballs, the main outcome of our analysis is that the corresponding spectra are described by linear trajectories has expected from lattice QCD. Our prediction for the ground state mass is comparable with that addressed same years later in Ref. [2]. Moreover, this model is capable to describe quite well the
spectra of scalar mesons, the ρ and a1 vectors [3, 4]. Moreover, in Ref. [6] we propose a modification of the model to properly describe chiral symmetry breaking beyond the inner structure of the pion. Finally, in Ref. [7] also the hybrid spectra have been evaluated. In conclusion, a good description of several observables is remarkably provided with only few not flexible parameters.
References
[1] M. Rinaldi and V. Vento, Eur. Phys. J. A 54, 151 (2018)
[2] E. Klempt, K. V. Nikonov, A. V. Sarantsev and I. Denisenko, Phys. Lett. B 830, 137171 (2022)
[3] M. Rinaldi and V. Vento, J. Phys. G 47, no.5, 055104 (2020)
[4] M. Rinaldi and V. Vento, J. Phys. G 47, no.12, 125003 (2020)
[5] M. Rinaldi and V. Vento, Phys. Rev. D 104, no.3, 034016 (2021)
[6] M. Rinaldi, F. A. Ceccopieri and V. Vento, Eur. Phys. J. C 82, no.7, 626 (2022)
[7] M. Rinaldi and V. Vento, [arXiv:2402.11959 [hepph]].
The PrimExeta experiment at Jefferson Lab is conducting a new measurement of the radiative decay width of the $\eta$meson via the Primakoff effect from the $\eta$meson photoproduction off a helium
nucleus. The produced $\eta$meson can be reconstructed by detecting either $\eta \to 2\gamma$ or $\eta \to 3\pi$ decays. A precise measurement of $\Gamma(\eta \to \gamma\gamma)$ will improve the
calculation of all $\eta$meson partial decay widths, particularly enhancing the understanding of the hadronic contribution to the muon magnetic moment from lattice QCD. Furthermore, it will provide
critical input to determine the $\eta$$\eta'$ mixing angle and the light quark mass ratio in a modelindependent manner. The status of the data analysis and its challenges will be presented in this
talk.
The ElectronIon Collider (EIC) stands as a groundbreaking facility to illuminate the subatomic world, particularly the structure of nuclear matter. This presentation explores the EIC's potential as a new 'pentaquark factory', enabling not only the discovery of new pentaquarks, but also the precise characterization of their properties. Its extraordinary luminosity and spin polarization capabilities will unlock a new era in exotic hadron research. In this talk, I will demonstrate how the spinpolarized electronproton collisions at the EIC can produce abundant pentaquarks and determine their spin and parity. Focusing on a heavy pentaquark p_c (uudccbar) and a light pentaquark p_s (uudssbar), both produced via photoninduced processes, the vectormeson dominance model is employed to analyze their production cross sections. This talk draws upon studies published in PRD 105 (2022) 11, 114023 and in arXiv:2402.07392.
This talk presents unprecedented correlation measurements involving Λ, Ξ, kaons and pions obtained by ALICE in pp collisions at 𝑠√
= 13 TeV. Several measurements are presented for the first time, constituting new experimental constraints on the S = −1, −2 mesonbaryon interactions and the nature of exotic states. The strong interactions involving mesons and baryons with strangeness content deliver a rather broad spectrum of interesting states, arising from the rich interplay between the elastic and inelastic QCD dynamics. The Λ(1405) in the S = −1 sector is an example of such molecular state, but in order to build a solid description of its inner structure more data are needed, particularly below the K ̄ N energy threshold. Much less experimental data are currently available on another potential molecular state, the Ξ(1620), predicted and observed in the S = −2 mesonbaryon sector. The presented correlation data put new constraints on these sectors and deliver a better understanding on such states.
Experimental data on the interaction between vector mesons and nucleons are a crucial input for understanding the pattern of inmedium chiral symmetry restoration (CSR) and dynamically generated excited N($\Delta$) states. However, accessing these interactions is hampered by the shortlived nature of the vector mesons, making traditional scattering experiments unfeasible. In recent years the ALICE Collaboration employed femtoscopy to measure similar challenging systems like the p$\mbox{}\Omega$ and $\phi\mbox{}$p. Leveraging the excellent PID capabilities of the ALICE experiment, coupled with the copious production of $\rho^{0}$p pairs at the LHC in small colliding systems, ALICE presents the firstever measurement of the momentum correlation function between $\rho^{0}$ and p. This measurement represents an unprecedented opportunity to study the nature of the excited N($\Delta$) in particular N(1700) and N(1900), possibly unveiling if these states are molecular in nature as well as shedding light on possible signatures of CSR at LHC energies.
This talk will present recent experimental findings at BESIII, encompassing three distinct studies. Firstly, the search for the production of deuterons and antideuterons in e+e annihilation at centerofmass energies between 4.13 and 4.70 GeV is discussed. The investigation aims to unravel the production mechanisms and properties of these light nuclei, shedding light on the dynamics of hadronization and quarkgluon interactions. Secondly, the measurement of the Born crosssection of e+e− → Σ+ antiΣ− at centerofmass energies between 3.510 and 4.951 GeV is addressed. This study provides valuable insights into the production of Σ+ antiΣ− pairs in e+e collisions, contributing to our understanding of hadron dynamics in this energy regime. Finally, the observation of significant flavorSU(3) breaking in the kaon wave function at 12 GeV^2<Q^2<25 GeV^2 and the discovery of the charmless decay ψ(3770) → K0S K0L are discussed. These results offer new perspectives on the flavor dynamics within the kaon wave function and the rare decay processes involving the ψ(3770) resonance.
In this paper, we conduct a Monte Carlo simulation study to investigate the production of strange and multistrange hadrons in highmultiplicity protonproton collisions. Our objective is to refine and validate the hadronic interaction models crucial for air shower simulations such as EPOS, QGSJET, SIBYLL, and PYTHIA. These models play a pivotal role in predicting the propagation of extensive air showers in the atmosphere and comparing them with experimental data from cosmic ray observatories such as highmultiplicity protonproton collisions in the ALICE experiment. In the case of (K0S) mesons, at low multiplicity classes, we found that EPOS and PYTHIA can show a better prediction of the data than QGSJET and SIBYLL, while QGSJET exhibits favorable predictions at higher multiplicity classes. On the other hand, when looking at (Λ) baryons, the EPOS model is the only model that shows the best comparison to data. In addition, We employ the Tsallis distribution to extract the effective temperature (Teff) and the nonextensivity parameter (q).
$K_1$ and $K^*$ are chiral partners, both with vacuum widths smaller than 100 MeV, making them a suitable pair that can be realistically measured.
Based on the fact that the mass difference between the chiral partners is an order parameter of chiral phase transition and that the chiral order parameter reduces substantially at the chemical freezeout point in ultrarelativistic heavy ion collisions, we argue that the production ratio of $K_1/K^*$ in such collisions should be substantially larger than that predicted in the statistical hadronization model. We further show that while the enhancement effect might be contaminated by the relatively larger decrease of $K_1$ meson than $K^*$ meson during the hadronic phase, the signal will be visible through a systematic study on centrality as the kinetic freezeout temperature is higher and the hadronic life time shorter in peripheral collisions than in central collisions. The work is based on PLB819 (2021) 136388 and arXiv:2310.11434.
Strangeness production in heavyion collisions reveals the modification of the properties of strange hadrons in hot and dense nuclear matter. Adopting inmedium properties of antikaons $(\bar K = K^, \bar K^0)$ described by the selfconsistent coupled channel unitarized scheme based on a SU(3) chiral effective Lagrangian (Gmatrix), we study strangeness production in heavyion collisions within the offshell PartonHadronString Dynamics (PHSD) transport approach. The inmedium modification of kaons $(K = K^+, K^0)$ are accounted via the kaonnuclear potential, which is proportional to the local baryon density. Our results such as the rapidity distributions, ptspectra, collective flows of (anti)kaon are found consistent with the experimental data on (anti)kaon production from the KaoS, FOPI and HADES Collaborations. Moreover, we demonstrate the sensitivity of kaon observables to the equationofstate of nuclear matter.
We also study hidden strangeness production within inmedium effects realized by a width broadening which reflects the chiral symmetry partial restoration. Implementing novel mesonbaryon and mesonhyperon production channels for $\phi$ mesons, calculated within a Tmatrix coupled channel approach based on the extended SU(6) chiral effective Lagrangian model, along with the collisional broadening of the $\phi$ meson inmedium spectral function, we find a substantial enhancement of $\phi$ meson production in heavyion collisions, especially at sub and nearthresholds, as shown in the experimental data at the HADES and STAR Collaborations. This allows to describe the experimentally observed strong enhancement of the $\phi/K^$ ratio at low energies without including hypothetical decays of heavy baryonic resonances to $\phi$ as in alternative approaches. Our results support that the modifications of open and hidden strangeness hadrons in nuclear medium are necessary to understand various experimental data.
The Compressed Baryonic Matter (CBM) experiment is under construction at the Facility for Antiproton and Ion Research (FAIR). It aims to explore the phase structure of strongly interacting (QCD) matter at large netbaryon densities and moderate temperatures by means of heavyion collisions in the energy range sqrt(s_NN) = 2.9  4.9 GeV. As fixedtarget experiment, CBM is equipped with fast and radiation hard detector systems and an advanced triggerless data acquisition scheme. The CBM experiment will measure at interaction rates of up to 10 MHz by performing online 4D (spacetime) reconstruction and even selection, thus allowing measurements of rare probes not studied so far such as multistrange hadrons and their antiparticles, doublestrange hypernuclei and dileptons.
This contribution will be an overview of the CBM physics goals among which are the equationofstate of compressed nuclear matter, the possible phase transition from hadronic to partonic phase, and chiral symmetry restoration. The CBM physics performance in terms of (multi)strange particle production, dilepton spectroscopy, fluctuations, and collective phenomena will be discussed. In addition, the status of preparations towards CBM commissioning in 2027, including performance evaluation of the CBM components at FAIR Phase0 experiments and the latest results of a CBM demonstrator testsetup operating with SIS18 beams (mCBM), will be presented.
Direct photons produced in heavy ion collisions are penetrating probes
and as such encode the entire spacetime history of the collision, from
the initial hard scattering till the final kinetic freezeout. For the
very same reason theoretical models are challenged to connect and balance
many different production mechanisms. Simultaneous observation of large
yields and large azimuthal asymmetries (elliptic flow) by PHENIX could so
far not been reproduced quantitatively, a situation dubbed "direct photon
puzzle". Using the 2014 200 GeV Au+Au data, which have ten times the
statistics of earlier published results, and deploying the same analysis
technique over the wide 0.8  10 GeV/c transverse momentum range, PHENIX
remeasured both the direct and nonprompt photon yields and the direct
photon elliptic flow in finer centrality bins than before. In this
presentation we will discuss the results and their bearing on the
"direct photon puzzle".
There seem to exist two lightest axial mesons with charm whose masses are very similar but the associated widths and other properties are different. These mesons are denominated as D1(2430)D1(2430) and D1(2420)D1(2420). Although two mesons with similar masses are expected to exist, with such quantum numbers, within the traditional quark model, as we discuss the description of their decay widths and other properties requires contributions from mesonmeson coupled channel scattering. We present the amplitudes obtained by solving the BetheSalpeter equations which unavoidably lead to the generation of two axial resonances when mesons are considered as the degrees of freedom in the model. One of them is narrow and has properties in good agreement with those of D1(2420)D1(2420). The other pole is wider, but not wide enough to be related to D1(2430)D1(2430). Its position (mass) also does not match well with that of D1(2430)D1(2430). The situation improves when a bare quarkmodel state is included. Further, we calculate the scattering lengths for different channels and compare them with the available data from lattice QCD. Using arguments of heavy quark symmetry, we discuss possible differences between the scattering lengths coming from the lattice QCD calculations for the DπDπ and D∗πD∗π systems and the preliminary experimental data from the ALICE Collaboration on the DπDπ system. We present two models, which can produce compatible properties for the two lightest D1D1 states but result in different scattering lengths: one in agreement with the findings of lattice QCD and the other in agreement with the estimation obtained using the DπDπ results from the ALICE Collaboration. We present the correlation functions for both cases and discuss how femtoscopic physics can shed light on this issue.
(ePrint: 2312.11811 [hepph])
We examine which first order phase transitions are consistent with today's astrophysical constraints. In particular, we explore how a wellconstrained massradius data point would restrict the admissible parameter space and to this end, we employ the most likely candidates of the recent NICER limits of PSR J0030+0451. To systematically vary the stiffness of the equation of state, we employ a parameterizable relativistic mean field equation of state, which is in compliance with results from chiral effective field theory. We model phase transitions via Maxwell constructions and parameterize them by means of the transitional pressure $p_{\rm trans}$ and the jump in energy density $\Delta\epsilon$. This provides us with a generic setup that allows for rather general conclusions to be drawn. We outline some regions in the $p_{\rm trans}$$\Delta\epsilon$ parameter space that may allow for a phase transition identification in the near future. We also find that a strongly constrained data point, at either exceptionally large or small radii, would reduce the parameter space to such an extent that mass and radius become insufficient indicators of a phase transition.
We study quasinormal $f$mode oscillations in neutron star(NS) interiors within the linearized General Relativistic formalism. We utilize approximately 9000 nuclear Equations of State (EOS) using spectral representation techniques, incorporating constraints on nuclear saturation properties, chiral Effective Field Theory ($\chi$EFT) for pure neutron matter, and perturbative Quantum Chromodynamics (pQCD) for densities pertinent to NS cores. Our study reveals a weak correlation between $f$mode frequencies and individual nuclear saturation properties, but a robust linear relationship between the radii and $f$mode frequencies with extreme masses (1.34$M_{\odot}$ and 2.0$M_{\odot}$). However, for different masses on the NICER data, it has minimal overlap in the radius domain and differs in the frequency domain with our nucleonic EOS set. Interestingly, the same analysis corresponding a set of EOS with hadronquark phase transition lie very well within our NICERderived constraints in the radius as well as the $f$mode frequency domain, indicating a preference of hybrid EOS over the purely nucleonic ones for the first time.
The massive stars end their lives by supernova explosions leaving central compact objects that may evolve into neutron stars. Initially, after birth, the star remains hot and gradually cools down. We explore the matter and star properties during this initial stage of the compact stars considering the possibility of the appearance of deconfined quark matter in the core of the star. Nonradial oscillation in the newly born compact object is highly possible at the initial stage after the supernova explosion. Nonradial oscillations are an important source of GWs. There is a high chance for GWs from these oscillations, especially the nodeless fundamental (f) mode to be detected by nextgeneration GW detectors. We study the evolution in frequencies of nonradial oscillation after birth considering phase transition and predicting the possible signature for different possibilities of theoretical compact star models.
This study investigates the radial oscillations of hybrid neutron stars, characterized by a composition of hadronic external layers and a quark matter core. Utilizing a densitydependent relativistic meanfield model that incorporates hyperons and $\Delta$ baryons for describing hadronic matter, and a densitydependent quark model for quark matter, we analyze the ten lowest eigenfrequencies and their corresponding oscillation functions. Our focus lies on neutron stars with equationsofstate involving N, N+$\Delta$, N+H, and N+H+$\Delta$, featuring a phase transition to quark matter. Emphasizing the effects of a slow phase transition at the hadronquark interface, we observe that the maximum mass is attained before the fundamental mode's frequency diminishes for slow phase transitions. This observation implies the stability of stellar configurations with higher central densities than the maximum mass, called Slow Stable Hybrid Stars (SSHSs), even under small radial perturbations. The length of these SSHS branch depends upon the energy density jump between two phases and the stiffness of the quark EoS.
References
[1]Radial Oscillations of Hybrid Stars and Neutron Stars including Delta baryons:The Effect of a Slow Quark Phase Transition, arXiv:2401.07789 (2024).
Conventional highresolution techniques for $\beta$decay spectroscopy utilize highpurity germanium detectors to measure individual $\gamma$ rays emitted after $\beta$ decay. However, these measurements are affected by the Pandemonium systematic error [1], resulting in many highenergy $\gamma$ rays and a significant portion of the $\beta$ strength being missed. The Total Absorption $\gamma$ray Spectroscopy (TAGS) technique effectively addresses this issue [2, 3]. It relies on detecting the full energy of $\gamma$ cascades following the decay, achieved through the use of large, highefficiency scintillation crystals acting as calorimeters. This technique allows for a Pandemoniumfree determination of the $\beta$ strength, a fundamental quantity that depends on the underlying nuclear structure, thus the ideal tool for constraining theoretical models.
The TAGS technique has been successfully utilized in $\beta$decay studies for many years, yielding important results relevant to nuclear structure, nuclear astrophysics, and applications in reactor and neutrino physics (see Ref. [3] for a recent review). In my talk, I will highlight some selected achievements. I will then introduce Experiment E891_23 [4], which has been granted beam time at the GANIL laboratory in France. The experiment aims to measure the $\beta$decay properties of several protonrich nuclei in the CrZn region, of significant interest for both nuclear structure [5, 6] and nuclear astrophysics. This experiment will be performed with a newconcept hybrid spectrometer, STARS, currently under development within the (NA)$^{2}$STARS project [7]. STARS will be the world’s first device to combine the large $\gamma$ efficiency characteristic of TAGS calorimeters with the superior energy resolution and timing of LaBr$_{3}$(Ce) crystals. This unique combination will enable unprecedented studies further away from nuclear stability.
[1] J.C. Hardy et al., Phys. Lett. B 71, 307 (1977).
[2] B. Rubio et al., J. Phys. G Nucl. Part. Phys. 31, S1477 (2005).
[3] A. Algora et al., Eur. Phys. J. A 57, 85 (2021).
[4] Experiment E891_23: “Total Absorption Spectroscopy for Nuclear Structure and Nuclear Astrophysics” (spokespersons: M. Fallot, S.E.A. Orrigo, A.M. Sánchez Benítez), approved by the GANIL Program Advisory Committee, Nov. 2023.
[5] S.E.A. Orrigo et al., Phys. Rev. Lett. 112, 222501 (2014).
[6] S.E.A. Orrigo et al., Phys. Rev. C 93, 044336 (2016).
[7] Project (NA)$^{2}$STARS: “Neutrinos, Applications and Nuclear Astrophysics with a Segmented Total Absorption with a higher Resolution Spectrometer” (spokesperson: M. Fallot), endorsed by the GANIL Scientific Council, Jan. 2023.
The measurement of a permanent electric dipole moment (EDM) in atoms is crucial for understanding the origins of CPviolation. Quadrupole and octupole deformed nuclei exhibit significantly enhanced atomic EDM. However, accurate interpretation of the EDM in such systems requires the characterization of their deformation. While nuclear deformation is indicated in various structure models, experimental confirmation, particularly in heavy isotopes essential for EDM measurements, is lacking.
Nuclear E$2$ $\gamma$ray transitions allow access to quantify quadrupole deformation, but these transitions are often mixed with M$1$ transitions. Both E$2$ and M$1$ transitions are well characterized by Weisskopf estimates, which rely on a singleparticle approximation. However, deviations from measurements arise due to collective nuclear deformation. To utilize E$2$ and E$2$+M$1$ transition lifetimes for determining quadrupole deformation, accurate Weisskopf estimates for heavy nuclei are essential. Currently, Weisskopf estimates are only available for the mass range $A<150$.
This work extends Weisskopf estimates for nondeformed nuclei in the mass range $150 < A < 250$, aided by theoretical structure models. This facilitates a comprehensive study of the deviation of E$2$ and M$1+$E$2$ transition lifetimes from the newly established Weisskopf estimates in deformed isotopes. Estimates of collective nuclear quadrupole deformation in isotopes relevant to EDM measurements, obtained from M$1+$E$2$ transition lifetimes, will be presented, also aiding in the identification of isotopes lacking definitive measurements for quadrupole deformation.
The neutronrich isotopes of hydrogen, such as $\rm ^{6}H$ and $\rm ^{7}H$, are good platforms for the study of NN interactions in neutronrich environments because they have the largest neutrontoproton ratios known so far. However, the experimental and theoretical studies of them are still limited. For $\rm ^{6}H$, the energy of its ground state is still controversial. It is about 2.7 MeV (above the $\rm ^{3}H$+3n threshold) in some experiments but about 6.6 MeV in others. The actual location of the $\rm ^{6}H$ ground state remains an open problem in theoretical work as well.
To solve this puzzle, $\rm ^{6}H$ is studied for the first time in an electron scattering experiment with the reaction $\rm ^{7}Li(e, e'p\pi^{+})^{6}H$ at MAMIA1. The 855 MeV electron beam of the Mainzer Microtron (MAMI) is used to hit a $\rm ^{7}Li$ target. The scattered electron, the produced proton, and $\pi^{+}$ are measured with high resolution and accuracy by the threespectrometer setup in the A1 hall. With the triple timing coincidence and momentum measurements of three spectrometers, the missing mass spectrum of $\rm ^{6}H$ can be obtained. In this talk, we will present the principle experiment, the experimental setup, and data analysis, including corrections and calibrations of the data. Our measurement of the $\rm ^{6}H$ ground state energy will be shown and compared with previous measurements and theoretical expectations.
Deviations from the typical liquiddroplike saturated density of the nucleus are a focal point in the exploration of nuclear structure. Phenomena of nucleon localisation, such as clustering or bubble structures, provide a distinctive perspective on the macroscopic consequences of nuclear interaction.
We performed a protontransfer direct reaction to probe the wavefunction of $^{46}$Ar and extrapolated the probability of population of the $d_{3/2}$ holestate relative to the $s_{1/2}$ in $^{47}$K.
The experiment, performed at the Spiral 1 facility in GANIL with a postaccelerated radioactive $^{46}$Ar beam impinging on a highdensity cryogenic $^{3}$He target relied on a stateoftheart experimental setup for a precise reconstruction of the kinematics of the reaction.
The heavy reaction fragment was identified by the highacceptance magnetic spectrometer, VAMOS, while the highgranularity silicon DSSSD detector, MUGAST, allowed the measurement of the angular distribution of the light ejectile while also performing particle identification. The AGATA gammaray tracking germanium array measured the gamma rays produced by the decay of the $^{47}$K excited states.
Our experimental findings strongly suggest an empty $s_{1/2}$ orbital, corroborated by ab initio calculations, thereby supporting the existence of a bubble phenomenon within this nucleus. This comparison between theory and data serves as a compelling indication of the observed nuclear structure phenomenon.
A reliable prediction of electroweak processes involving a nucleus is required to further understand nuclear structure and other related topics, such as nucleosynthesis and particle physics. In the past two decades, the range of applicability of nuclear ab initio calculations has been rapidly extending and reaching mass number of 200 systems. Yet, the reproduction of magnetic dipole moment, especially in medium and heavy mass regions, is one of the major challenges in nuclear ab initio calculations. In this presentation, I will show the ab initio calculation results of magnetic dipole moments for medium and heavy mass nuclei and discuss the effect of the leadingorder twobody current.
In this contribution, I will present a short, personal overview of nuclear Density Functional Theory (DFT). Two specific aspects will be emphasised. Compared to socalled ab initio approaches, DFT is more phenomenological; however, it can be applied throughout the whole isotope chart and account for many observables that
ab initio cannot handle so far like, for instance, the excited states of mediumheavy nuclei. Accordingly, I will focus on nuclear response calculations and discuss the status of collective and singleparticle properties by using a few illustrative examples. Then,
I will advocate the need of grounding DFT on ab initio as has been done for Coulomb systems, and discuss the status and perspectives for this challenging task.
Photoproduction of hadrons is an important experimental tool to understand the generation of hadrons as bound systems of quarks and gluons in the nonperturbative regime of QCD. In the lightbaryon sector, advancements in understanding the excited states of the nucleon were achieved by measuring single and double polarization observables using polarized photon beams and polarized targets at experimenal facilities like the A2 experiment in Mainz and the CBELSA/TAPS experiment in Bonn with photon beam energies of up to 3 GeV.
Higher photon beam energies of up to 12 GeV are used at the GlueX experiment, which is a photoproduction experiment located in Hall D of Jefferson Lab, with the primary goal of studying the spectrum of lightquark hybrid mesons. The maximum available beam energy provides in addition the exciting opportunity to study photoproduction of the bound charmonium states near threshold and search for potential pentaquark states like the $P_c$ states found at LHCb.
Selected hadron spectroscopy results from different photoproduction experiments will be presented.
It is important to obtain information on YN and YY interaction from study of structure of hypernuclei. For this purpose, I have been studying $\Lambda$ hypernuclei for $\Lambda N$ interaction. In this conference, I will report of structure of $\Xi$ hypernucei and $\Xi N$ interactions.
Neutron stars (NSs) are unique laboratories to probe matter in extreme conditions that
cannot be currently reproduced on Earth. Nuclear physics experiments, in tandem
with astrophysical observations, can give valuable insight into the properties
of dense matter encountered in these stellar objects.
The connection between astrophysical observations and microphysical properties of
NSs requires both microscopic and macroscopic (global) modelling. For cold (mature), slowly rotating, and isolated NSs, this connection mainly relies on the knowledge of the equation of state (EoS).
In this presentation, I will give a brief introduction on the NS EoS, in connection with current constraints coming from both nuclearphysics and astrophysics. The prediction for NS properties and observables obtained using different EoSs (with their associated uncertainties) will be also presented in relation with recent (multimessenger) astrophysical observations.
We are all individuals made up of a unique combination of characteristics and experiences, some of which assist us in our physics careers while others make us feel we don’t belong. In this talk I will use my own journey to highlight issues of diversity and inclusion. How, as a woman physicist, I went from understanding how my personal experiences were actually part of a wider picture of gender inequality, and finding networks where I felt I belonged, to broader diversity issues then to intersectionality bringing us back to the uniqueness of the individual.
CEBAF at Jefferson Lab delivers the world's highest intensity and highest precision multiGeV electron beam to study strong interactions in the nonperturbative regime. The current program at 12 GeV is well underway and the CEBAF community is looking toward its future at the science that could be obtained through a future upgrade at higher beam energy. JLab at 22 GeV will provide unique, worldleading science with highprecision, highluminosity experiments elucidating the properties of quantum chromodynamics (QCD) in the valence regime (x_B ≥ 0.1). With a fixedtarget program at the “luminosity frontier”, large acceptance detection systems, as well as highprecision spectrometers, CEBAF will continue to offer unique opportunities to shed light on the nature of QCD and the emergence of hadron structure. The combination of JLab highintensity experiments and results obtained by the future Electro Ion in Collider in complementary kinematics will give scientists the full suite of tools to understand how QCD builds hadronic matter.
The Super Tau Charm Facility (STCF), a planned symmetric electronpositron collider in China, aims to facilitate $e^+e^−$ collisions across a centerofmass energy range of 2 to 7 GeV, targeting a peak luminosity of $0.5×10^{35}\mathrm{cm}^{−2}\mathrm{s}^{−1}$. With an anticipated annual integrated luminosity exceeding $1~ab^{−1}$, the STCF is poised to generate vast datasets. These will enable precision measurements of XYZ particles' properties, exploration of new CP violation sources within strangehyperon and taulepton sectors, and accurate Cabibbo angle ($\theta_c$) measurements to test the unitarity of the CKM matrix; search for anomalous decays with sensitivities extending down to the level of SMmodel expectations, among other objectives. This talk will cover the STCF's physics goals and outline the latest advancements in the project’s R&D.
The CERN secondary beam lines of the North and the East Area are designed to deliver beams of secondary and tertiary particles as well as attenuated primary protons and ions from the SPS and PS accelerators. With its diverse portfolio, the CERN experimental areas serve over 200 test beams and experiments per year with more than 2000 users. In context of the Physics Beyond Colliders (PBC) initiative, various new ideas have been presented for exploiting the full scientific potential and intensity for fixed target experiments. These include experiments like AMBER, in the QCD sector, with a rich physics programme ranging from proton radius measurements to meson structure studies, as well as experiments addressing BSM physics, like NA64 and ShiP/BDF, requiring high intensity beams. Requests for different species and high intensities of ion beams have also been brought forward by the NA61 and NA60++ collaborations. Various developments and upgrades are therefore being studied and planned for the CERN North and East Area beams during and after the Long Shutdown 3 to be able to serve these diverse requests. The presentation will include an overview of the existing beam lines and facilities at the CERN North and East Area, as well as showcase the upcoming plans for consolidation and upgrades to ensure the optimal physics operation and test beam runs for the coming decades.
One of the future plans at Jefferson Lab is running electron scattering experiments with large acceptance detectors at luminosities of 1037 cm−2s−1. These experiments allow the measurements of the Double Deeply Virtual Compton Scattering (DDVCS) reaction, an important physics process in the formalism of Generalized Parton Distributions, which has never been measured because of its low rate. The luminosity upgrade of CLAS12 or the SOLID detector makes Jefferson Lab a unique place to measure DDVCS. One of the important components of this upgrade is a tracking detector that can withstand high rates of ≈ 1MHz/cm2. The recently developed Microresistive well (μRWELL) detectors are a promising option for such a tracking detector by combining good position resolutions, low material budget with simple mechanical construction and low production costs. In my talk, I will show the recent developments and studies with μRWELL detectors at Jefferson Lab for future upgrades of the CLAS12 detector to study the DDVCS reaction.
The suppression of the structure functions of bound nucleons in nuclei com pared to those of free nucleons, observed in deep inelastic scattering experiments, is known as the EMC effect. Its origin is an open question and there is no general explanation for it.
The deuteron is a great system to study the EMC effect. It is a bound system, thus the nucleon structure functions are expected to be modified compared by their free nucleon counterpart. On the other side, we can measure the recoil spectator nucleon (tagging) which was not part in the deep inelastic scattering reaction off the deuteron. This allows to determine the initial state of the scattered nucleon.
The Large Angle Detector experiment at Jefferson Lab (LAD) plans to mea sure the structure function of the neutron on deuteron involving high momentum nucleons, through the spectator tagging method in the DIS process, measuring the recoil proton at large angles. Such as configuration, will reduce final state interactions and result in a clean signal of the DIS measurement and therefore, the structure function.
In this talk, I will present the setup and the status of the LAD experiment to be run in Fall 2024.
I will discuss the recent progress in understanding photo production of hybrid mesons
The GlueX experiment at Jefferson Lab was specifically designed for precision studies of the lightmeson spectrum. A photon beam with energies of up to 12 GeV is directed onto a liquid hydrogen target contained within a hermetic detector with nearcomplete neutral and charged particle coverage. Linear polarization of the photon beam with a maximum around 9 GeV provides additional information about the production process. In 2018, the experiment completed its first phase, recording data with a total integrated luminosity above 400 pb$^{1}$. We will highlight a selection of results from this worldleading data set with emphasis on the search for light hybrid mesons. In the mean time, the detector underwent significant upgrades and is currently recording data with an even higher luminosity. The future plans of the GlueX experiment to search for exotic hadrons with unprecedented precision will be summarized.
Highstatistics total crosssections for the vector meson photoproduction at the threshold: $\gamma p \to \omega p$ (from A2 at MAMI), $\gamma p \to \phi p$ (from CLAS at JLab), and $\gamma p \to J/\psi p$ (from GlueX at JLab) allow to extract absolute value of vector meson nucleon scattering length using Vector Meson Dominance model. The “young” vector meson hypothesis may explain the fact that the obtained scattering length value for $\phi$ meson nucleon compared to typical hadron size of 1 fm indicates that the proton is more transparent for phimeson compared to the omegameson and is much less transparent that $J/\psi$meson. The extended analysis of the upsilonmeson photoproduction using quasidata from the QCD approach is in perfect agreement with the light meson finding using experimental data.
Recent high statistical $J/\psi$ photoproduction cross sections measured by the GlueX collaboration allow to search for the exotic $P_c(4312)$ state observed by the LHCb collaboration. The fits show that destructive interference involving an Swave resonance and associated nonresonance background produces a sharp dip structure about 77 MeV below the LHCb mass, in the same location as a similar structure is seen in the data. The interference between open charm and gluon exchange may (by some accident) produce a dip, but there is room for the resonance.
Future EIC and EicC high quality experiments will have a chance to evaluate cases for J/psi and Upsilonmesons. It allows us to understand dynamics of $c\bar{c}$ and $b\bar{b}$ production at the threshold and to look for the effect of LHCb $P_c(4312)$. JPARC ability to measure $\pi^p \to \phi n$ and $\pi^p \to J/\psi n$, which are free from VMD, is evaluated.
The GlueX experiment at Jefferson Lab aims to map the spectrum of light mesons through photoproduction, with a focus on searching for hybrid mesons, a predicted category of hadrons containing excited gluonic degrees of freedom. Achieving this goal requires a precise theoretical understanding of the underlying production mechanisms. In the GlueX energy regime, single meson photoproduction processes with a polarized photon beam are governed by the exchange of Regge trajectories in the tchannel, with unnatural parity exchanges, such as pion exchange, dominating in chargeexchange reactions at small momentum transfer. In this talk, I will explore pion photoproduction as it offers the cleanest way to study the pion exchange mechanism. However, the tchannel pion exchange process is not gauge invariant by itself, requiring consideration of the Born diagrams corresponding to the s and uchannel nucleon exchanges. This raises the crucial question of how to properly reggeize the pion exchange amplitude. I will show that the electric term of the nucleon Born diagrams contains a “pion pole” that arises from kinematical factors and which is responsible for restoring gauge invariance of the pion exchange amplitude. I will also present a novel approach to reggeize the pion pole which considers explicitly the exchange in the tchannel of all the mesons in the pion trajectory [1].
[1] G. Montana, et al. (JPAC Collaboration) (in preparation)
The GlueX experiment at Jefferson Laboratory seeks to map out the spectrum of light mesons produced from a linearly polarized photon beam. The production and decays of a light meson resonance $X$ such as $\gamma p\rightarrow Xp' \rightarrow \omega\pi^0 p'$ can be modeled with polarized vectorpseudoscalar amplitudes, which can describe the contribution of individual amplitudes to the total measured intensity. The status of massindependent fits to the $\omega\pi^0$ mass spectrum over a wide mass and $t$ range will be presented, with a particular focus on the observed production process of the $b_1(1235)$ meson. Additionally, we will present a complementary polarized moment analysis for the vectorpseudoscalar process. Though moments lack immediate physical interpretation their basis has unique solutions by construction, allowing one to better understand consistency between repeated fit results. Their physical meaning can be recovered by translating back to the partial wave basis. The results of these analyses will enhance our understanding of how the various states of light mesons are produced.
The PRad experiment, performed recently in Jefferson Lab, demonstrated the advantages of the calorimetric method over the previously used magnetic spectrometer technique in scattering experiments to measure the proton charge radius with a high accuracy. Our first result, within the experimental uncertainties, agreed with the small radius extracted from the muonic hydrogen spectroscopy experiments, and made a significant input in changing the value of the proton charge radius in the recent CODATA recommendations. With that, the PRad result came in a direct disagreement with all modern electron scattering experiments including the most precise single scattering experiment recently performed in Mainz/MAMI in both the extracted radius and the measured form factors at very low Q2. The Prad collaboration is currently preparing a new, upgraded high accuracy experiment (PRadII) to run in Fall of 2025. With its factor of four improvement in experimental uncertainties PRadII will address these yet unsettled controversies in the field of subatomic physics. The current status of this experiment will be presented and discussed in this talk.
In the context of the anomalous magnetic moment of the muon, the hadronic contribution plays a crucial role, especially concerning the error budget estimation. Currently, lattice QCD simulations confront the dispersive calculations based on e+e hadronic cross sections. The new MUonE experimental proposal pretends to shed light on that situation. Still, a powerful method to extract the desired hadronic contribution from such a new experiment should be devised. In this talk, we will show how accelerationofconvergence methods profiting from the analyticity of the correlator driving the hadronic contribution are key to reaching the required precision.
Fragmentation functions are indispensable for understanding processes of hadron production ubiquitously existing in highenergy collisions, but their first principle determination has never been realized due to the NPhard nature in traditional lattice calculation. We propose a framework that makes a first step for exploiting quantum computing to evaluate the Parton fragmentation function. The key subroutine is to construct a hadron projector for filtering out hadrons of desired types in a collection of particles encoded in the quantum state. Remarkably, We show that the hadron projector can be constructed efficiently with a variational quantum algorithm. We illustrate the framework by elaborating on the Nambu–JonaLasinio model with numeral simulations. Moreover, we develop error mitigation techniques tailed for accurately calculating the fragmentation functions in the presence of quantum noises. Our work opens a new avenue for investigating fragmentation on nearterm quantum computers.
We present recent efforts in the determination of the distribution of partons in the pion, with an emphasis on uncertainty quantification. The Fantômas project aims to explore the role of trial shapes for the distribution of quarks and gluons in the final uncertainty that results from global analyses. The first results within the Fantômas framework show that impact for PDFs of the pion, which is now the only PDF set that contains an explicit sampling over parametrization space. We’ll comment on future avenues for uncertainty quantification in global analyses of PDFs.
Selected experimental measurements on quarkonium production in protonproton and heavyion collisions will be presented. Particular attention will be given to those that could help us to build a unified physics picture which can reconcile our understanding of particle production in all collision systems.
The investigation of heavy quarkonia can give insight into processes that occur during the evolution of the quarkgluon plasma and therefore allow conclusions about the properties of the medium. One advantage of the theoretical approaches is that due to the large masses of the heavy quarks it is possible to describe them nonrelativistically. We choose a classical model to describe charm and anticharm quarks as Brownian particles in the background medium of light quarks and gluons. The motion of the heavy quarks and the interaction with the medium are based on a FokkerPlanck equation, which can be realized with Langevin simulations, quantifying how position and momentum of the quarks change due to random kicks from the medium. The heavy quarks are able interact over a Coulomblike screened potential to form bound states, which can later dissociate again due to interactions with the medium. Therefore dissociation and regeneration of charmonium states can be described. The medium evolution is parametrized by a transversally expanding, boost invariant fireball. Box simulations at fixed temperature and volume are used to verify that the system reaches the expected thermal distribution in the equilibrium limit and to test bound state properties. Within the fireball model, the initial momentum distribution of the pairs results from the PYTHIA eventgenerator and the elliptic flow of charm and anticharm quarks as well as of charmonia is studied at RHIC and at LHC energy.
We discuss the flow harmonics or the elliptic and triangular flow of J/ψ, ψ(2S), and χc1(1P) mesons in heavy ion collisions. Starting from the investigation on transverse momentum distributions of those charmonium states, we calculate their elliptic and triangular flow when they are produced at the quarkhadron phase boundary by quark recombination. We show that the wave function distribution of charmonium states plays a significant role, especially in producing charmonium states, leading to the transverse momentum distribution of the ψ(2S) meson as large as that of the J/ψ meson. On the other hand, we find that the wave function effects and feeddown contributions are averaged out for elliptic and triangular flow, resulting in similar elliptic and triangular flow for all charmonium states. We further investigate the elliptic and triangular flow of charmonium states at low transverse momentum regions and discuss the quark number scaling of elliptic and triangular flow for charmonium states in heavy ion collisions.
arXiv:2307.14765
QTRAJ is a computer code that simulates the propagation of quarkonium in the quarkgluon plasma (QGP) based on the quantum trajectories' algorithm. This algorithm solves a master equation in which the quarkonium is treated as an open quantum system (OQS). The specific master equation is obtained through the potential nonrelativistic QCD (pNRQCD) approach, but so far has been restricted to the regime rT << 1, where r is the size of the color dipole and T is the temperature. This limit is accurate for $\Upsilon(1S)$ but the applicability to other quarkonium states is dubious.
A major advantage of this approach is that it turns a 3D spatial evolution into a 1D Schrödinger equation with a nonhermitian Hamiltonian, drastically reducing the computational cost.
We generalize the code by extending to the regime rT ~ 1 in the onegluon exchange approximation. This is done by implementing new jump operators between the resonances and expanding them in plane waves, giving rise to a variation of the algorithm present in QTRAJ 1.0. We will be showing a review of this approach comparing the rT<<1 and rT~1 cases, and we will discuss prospect for phenomenological application to excited states.
Being able to deal with the most acurate methods to describe the $Q\bar Q$ evolution in a quark gluon plasma is a prerequisite to match the precise quarkonium measurements of all URHIC experiments. Following our recent work [1], we present exact numerical solutions in a onedimensional setting of quantum master equations previously derived in [2].
We focus on the dynamics of a single heavy quarkantiquark pair in a QuarkGluon Plasma in thermal equilibrium, in the socalled quantum Brownian regime where the temperature of the plasma is large in comparison with the spacing between the energy levels of the $Q\bar Q$ system. The onedimensional potential used in the calculations [2] has been adjusted so as to produce numbers that are relevant for the phenomenology of the charmonium.
The equations are solved using different initial states and medium configurations. Various temperature regimes are studied and the effects of screening and collisions thoroughly analyzed. Distinctive features of the $Q\bar Q$ evolution with the quantum master equations are presented. Some phenomenological consequences are addressed by considering evolutions of a single $b\bar b$ in both Bjorken scenario and EPOS4 temperature profiles.
Semiclassical approximation has been recently used [1,4] to describe charmonium production in URHIC, where many $c\bar c$ are implied. Obtaining an estimate of the systematic error attached to this approximation is of crucial importance to assess the agreement with experimental data. In the second part of the talk, we investigate the accuracy of the SC approximation by benchmarking the corresponding evolutions on the exact solutions derived with the QME for the case of a single $c\bar c$ pair.
refs:
1. S. Delorme et al., arxiv 2402.04488
2. J.P. Blaizot and M.A. Escobedo, JHEP06(2018)034
3. R. Katz, S. Delorme, P.B. Gossiaux, Eur. Phys. J. A (2022) 58:198
4. D.Y. Arrebato Villar et al., Phys.Rev.C 107 (2023) 5, 054913
The saturation properties of symmetric and asymmetric nuclear matter have been computed using the finite range simple effective interaction (SEI) having Yukawa form factor. The results for higher order derivatives of the energy per particle and the symmetry energy computed at saturation, namely,$Q_0$, $K_{sym}$, $K_\tau$, $Q_{sym}$, are compared with the corresponding range of values extracted from studies involving theory, experiment as well as astrophysical observations. The ability of the equations of state computed with this SEI in predicting the threshold mass for the prompt collapse in binary neutron star merger and gravitational redshift is analyzed in terms of the compactness of the neutron star and the incompressibility at the central density of the maximum mass star. The correlations existing between neutron star properties with the nuclear matter saturation properties have been analyzed and compared with the predictions of other model calculations.
The quest to constrain the equation of state (EoS) of ultradense matter and thereby probe the behaviour of matter inside neutron stars core is one of the main goals of modern astrophysics. A promising method involves investigating the longterm cooling of neutron stars, comparing theoretical predictions with various sources at different ages. However, limited observational data and uncertainties in source ages and distances have hindered this approach. In this talk, I will share results from an extensive study on dozens of thermally emitting isolated neutron stars. By reanalyzing XMMNewton and Chandra data and taking advantage of updated ages and distances, we identified three sources with unexpectedly cold surface temperatures for their young ages. To investigate these anomalies, we conducted magnetothermal simulations across diverse mass and initial magnetic field ranges, considering three different EoSs. We found that the "minimal" cooling model failed to explain the observations, regardless of mass or magnetic field, as validated by a machine learning classification method. The existence of these young cold neutron stars suggests that any dense matter EoS must be compatible with a fast neutrino cooling process, eliminating a significant portion of current EoS options according to recent metamodelling analysis.
In this talk I will present a method to compute the properties of dilute nuclear matter from quantum field theory at finite density. This approach provides a parameterfree calculation of the energy per particle of nuclear matter relying only on experimental nucleonnucleon phase shifts. As a practical application we will show our predictions for the equation of state of dilute symmetric and neutron matter. Our result for dilute neutron matter can be used to calculate the equation of state of neutron stars, as Eva Lope Oter will show in her talk.
We have recently provided the generic band of equations of state for matter at attainable densities in zero and finitetemperature neutron stars restricted only by hadronic physics and fundamental principles, which are crucial for testing General Relativity and theories beyond it. We also characterise any firstorder phase transitions therein by the specific latent heat, which we have systematically explored with these EoS for different interpolations. In addition, we used these GRindependent equations of state to constrain the quadratic Palatini gravity f($\mathcal{R}$).
In this work, we incorporate an EoS based on no potential, rather directly from nucleon scattering data [1] for pure neutron matter (PNM) at zero temperature and very low densities by interpolation up to known higherdensity physics, applying causality, monotonicity and thermal consistency, in two steps. We use a first interpolation between the uncertainty band obtained for PNM and the saturation density, constrained by nuclear experiments. Then, we use a second interpolation between this band and the highdensity perturbative QCD regime so we cover number densities in the range 10$^{8}\leq n < 7$ fm$^{3}$.
References
[1] J. M. Alarcón and J. A. Oller. Nuclear matter from the ladder resummation in terms of the experimental nucleonnucleon scattering amplitudes. Phys. Rev. C, 107(4):044319,2023.
Neutron stars unite several extremes of physics which cannot be recreated on Earth, making them excellent cosmic laboratories for studying the properties of ultradense matter. One exciting characteristic is the presence of superfluid and superconducting components in mature neutron stars. Albeit created under very different circumstances, such macroscopic quantum behaviour exhibits many similarities with terrestrial condensates, such as the superfluid phases in helium, ultracold atomic gases, heavyion collisions or superconducting transitions in metals.
In this talk, I will focus on the last relationship and discuss how we can describe the interiors of neutron stars using a twocomponent GinzburgLandau model, a framework wellknown from the study of laboratory superconductors. By adapting this description to the neutronstar interior and connecting it with realistic superfluid parameters and equations of state, we can determine the equilibrium properties of the superconducting component throughout the entire neutronstar core. I will specifically focus on equations of state based on the Skyrme functional, present the corresponding phase diagrams, and discuss how this approach provides insights into the mesoscopic magnetic flux distribution in neutronstar interiors.
LHCb has collected the world's largest sample of charmed hadrons. New measurements of direct and timedependent CP violation and of $D^0 \overline{D}^0$ mixing parameters are here presented, along with prospects for the sensitivity at the LHCb upgrades.
We study the $\Omega_c(3120)$, one of the five $\Omega_c$ states observed by the LHCb collaboration, which is well reproduced as a molecular state from the $\Xi^*_c \bar K$ and $\Omega^*_c \eta$ channels mostly. The state with $J^P = 3/2^$ decays to $\Xi_c \bar K$ in the $D$wave and we include this decay channel in our approach, as well as the effect of the $\Xi^*_c$ width [1]. With all these ingredients, we determine the fraction of the $\Omega_c(3120)$ width that goes into $\Xi_c \pi \bar K$, which could be a measure of the $\Xi^*_c \bar K$ molecular component, but due to a relatively big binding, compared to its analogous $\Omega(2012)$ state [2,3], we find only a small fraction of about 3\%, which makes this measurement difficult with present statistics. As an alternative, we evaluate the scattering length and effective range of the $\Xi^*_c \bar K$ and $\Omega^*_c \eta$ channels which together with the binding and width of the $\Omega_c(3120)$ state, could give us an answer to the issue of the compositeness of this state when these magnitudes are determined experimentally, something feasible nowadays, for instance, measuring correlation functions. I will give a presentation based on Ref. [1].
[1] N. Ikeno, W. H. Liang and E. Oset, arXiv:2312.13732 [hepph], accepted by PRD.
[2] R. Pavao and E. Oset, Eur. Phys. J. C 78, 857 (2018).
[3] N. Ikeno, G. Toledo, and E. Oset, Phys. Rev. D 101, 094016 (2020).
Some time ago, a tetraquark mixing model was proposed to explain the structure of the two nonets in the $J^P=0^+$ channel :
the light nonet, consisting of $a_0(980)$, $K_0^*(700)$, $f_0(500)$, $f_0(980)$,
and the heavy nonet, comprising $a_0(1450)$, $K_0^*(1430)$, $f_0(1370)$, and $f_0(1500)$.
In this talk, we will review the tetraquark mixing model and highlight its successful aspects, including
elucidating the mass differences of the two nonets, determining the coupling strengths of these nonets with two pseudoscalar mesons,
and identifying their decay modes.
Additionally, we will discuss how the hiddencolor components of the tetraquark mixing model substantially contribute to the hyperfine masses.
This strongly suggests that the two nonets are tetraquarks in the light quark system rather than being composed of hadronic molecules.
The discussion of light pentaquarks, which was once sparked by the good agreement between the theoretical prediction[1] and the first measurement of the $\Theta^+$[2], has become dormant after the subsequent null results of the $\Theta^+$ baryon from worldwide experiments. However, the recent observation of heavy pentaquarks by the LHCb Collaboration[3] has revitalized interest in pentaquark physics. Although the $\Theta^+$ is most unlikely to exist, we believe that a final attempt should be made for a definitive exclusion. In this talk, we will present the idea to search for the $S=+1$ pentaquark in $K^{+}d → K^0pp$ reaction using $K^+$ beam with a momentum of $p_{K+}=0.5$ GeV/c at JPARC. Our novel detector system, Hyperon Spectrometer, consisting mainly of a time projection chamber and a 1T superconducting magnet, will be utilized to exclusively measure the decay products of $\Theta^+$, such that $\Theta^+ \rightarrow K^0p$, followed by $K^0\rightarrow \pi^+\pi^$. The simulation results will be also presented to discuss the feasibility of the experiment.
[1] D. Diakonov, V. Petrov, and M. V. Polyakov, Z. Phys. A 359, 305 (1997).
[2] T. Nakano et al., (LEPS Collaboration), Phys. Rev. Lett. 91, 012002 (2003).
[3] R. Aaij et al. (LHCb Collaboration), Phys. Rev. Lett. 115, 072001 (2015).
Charm physics, which involves a heavy uptype quark, offers a unique environment in which to search for new particles and couplings beyond the Standard Model. Studies with charmed hadron decays complement those in B physics, expanding the potential to observe BSM phenomena. The Belle II experiment has an active charm physics program that includes studies of rare decays, CP violation, flavor mixing, and spectroscopy. This talk will include a review of the status and prospects for the charm physics program at Belle II.
The strong and electromagnetic interactions are two main decay mechanisms
in charmonium decays. The relative phase between them is a basic parameter in understanding the
decay dynamics, especially for the precise measurements. Based on indirect studies on Jpsi two body
decay modes: 10, 00, 11, and NNbar, the relative phase is around 90 degrees. There is also some results from psi(3686) which do not veto the 90 degrees possibility. From the theoretical point of view, both subamplitudes in perturbative QCD and QED should be real which means the relative phase should be 0 degree which is conflict with the indirect results. In this talk, we present the direct measurement with resonance scan method. By introducing the EM amplitude from continuum decay, the interference between EM and strong mechanism is measured in Jpsi decays to 5pi final state.
In this talk, based on the work [PRD109,054008], we develop a model aimed at understanding the three mass distributions of pairs of mesons in the Cabibbosuppressed $D^+_s \to K^+ \pi^+ \pi^$ decay recently measured with high statistics by the BESIII collaboration. The largest contributions come from the $\rho^0$ and $K^{*0}$ related decay modes, but the $K^*_0(1430)$ and $f_0(1370)$ modes also play a moderate role and all of them are introduced empirically. Instead, the contribution of the $f_0(500)$, $f_0(980)$ and $K^*_0(700)$ resonances is introduced dynamically generated in the chiral unitary approach. We pay special attention to the specific effects created by the light scalar resonances, which are visible in the low mass region of the $\pi^+ \pi^ (f_0(500))$ and $K^+ \pi^(K^*_0(700))$ mass distributions and a narrow peak for $\pi^+ \pi^ $ distribution corresponding to $f_0(980)$ excitation. The contribution of these three resonances is generated by only one parameter. We see the agreement found in these regions as further support for the nature of the light scalar states as dynamically generated from the interaction of pseudoscalar mesons.
We study the J/ψ → ϕπ+a0(980),(a0 → π−η) decay, evaluating the double mass distribution in terms of the π−η and π+a0 invariant masses. We show that the π−η mass distribution exhibitsthe typical cusp structure of the a0(980) seen in recent high statistics experiments, and the π+a0
spectrum shows clearly a peak around Minv(π+a0) = 1420 MeV, corresponding to a triangle singularity. When integrating over the two invariant masses we find a branching ratio for this decay ofthe order of 10−5, which is easily accessible in present laboratories.
We report the latest results from the spectroscopy of deeply bound pionic Sn 121 atoms performed at RIBF, RIKEN. We have determined the binding energies and the widths of the pionic orbitals and deduced the pionnucleus interaction with unprecedented precision. After extensive analysis, we deduced that the chiral condensate at nuclear saturation density is reduced by a factor of 60+3% (T. Nishi, K. Itahashi et al., Nature Phys. (2023) doi:10.1038/s4156702302001x). We also discuss the analysis status of systematic spectroscopy of pionic Sn isotopes and the future plans to deduce the density dependence of the chiral condensate.
In this note we study the tensor and vector exchange contributions to the elastic reactions involving the pseudoscalar mesons π+π−, K+K−and D+D−. In the case of the tensorexchange contributions we assume that an intermediate tensor f2(1270) is dynamically generated from the interaction of two virtual ρ mesons, with the use of a pole approximation. The results show very small contributions coming from the tensorexchange mechanisms when compared with those from the vectorexchange processes, of the order of 10^3, which make this contribution negligible. This gives support to the use of the chiral unitary approach based on the exchange of vector mesons. We explain why these results are even smaller than those previously found in [ecker].
[ecker] G. Ecker and C. Zauner, Eur. Phys. J. C 52, 315323 (2007).
The ALICE collaboration has recently reported pi+K_S femtoscopic correlations in pp collisions. Here we show [1] how they can be well described using existing realistic piK interactions obtained from a dispersive analysis of scattering data [2], containing an accurate description of the kappa/K0*(700) resonance pole.
[1] in progress: M. Albaladejo, A. Canoa, J.M. Nieves, J.R.Pelaez and E.RuizArriola
[2] J.R.Pelaez, A. Rodas,Phys.Rept. 969 (2022) 1126
Cusp structures in spectra represent discontinuities in the differential cross sections, which are widely observed at the thresholds of scattering channels.
In the K^ d→πΛN reaction, a cusp at the ΣN threshold exists in the ΛN invariant mass spectrum.
This study investigates the shape of the spectrum at the ΣN threshold by treating the scattering process as a twobody multiple scattering and describing it in terms of the scattering length and propagator.
Explaining gravitationalwave (GW) observations of binary neutron star (BNS) mergers requires an understanding of matter beyond nuclear saturation density. Our current knowledge of the properties of highdensity matter relies on electromagnetic and GW observations, nuclear physics experiments, and general relativistic numerical simulations. We perform numericalrelativity simulations of BNS mergers subject to nonconvex dynamics allowing for the appearance of expansive shock waves and compressive rarefactions. Using a phenomenological nonconvex equation of state we identify observable imprints on the GW spectra of the remnant. Nonconvexity regions may be associated with first order phase transitions from nuclear/hadronic matter to deconfined quark matter. We find that this dynamics induces a significant shift in the quasiuniversal relation between the peak frequency of the dominant mode and the tidal deformability (of order $Δf_{peak}≳380$ Hz) with respect to that of binaries with convex (regular) dynamics.
We investigate the intricate relationships between the nonradial (f) mode oscillation frequencies of neutron stars (NS)s and the corresponding nuclear matter equation of state (EOS) using a machine learning (ML) approach within the ambit of the relativistic mean field (RMF) framework for nuclear matter. With two distinct parameterizations of the Walecka model, namely, (1) with nonlinear self interactions of the scalar field (NL) and, (2) a density dependent Bayesian model (DDB), we perform a thorough examination of the (f) mode frequency in relation to various nuclear saturation properties. The correlations between the (f) mode frequencies and nuclear saturation properties reveal, through various analytical and ML methods, the complex nature of NSs and their potential as the cosmic laboratory for studying extreme states of matter. A principal component analysis (PCA) has been performed using mixed datasets from DDB and NL models to discriminate the relative importance of the different components of the EOS on the $f$ mode frequencies. Additionally, a {\it Random forest feature importance} analysis also elucidates the distinct roles of these properties in determining the (f) mode frequency across a spectrum of NS masses. Our findings are further supported by symbolic regression searches, yielding highaccuracy relations with strong Pearson coefficients and minimal errors. These relations suggest new methodologies for probing NS core characteristics, such as energy density, pressure, and speed of sound from observations of nonradial (f) mode oscillations of NSs.
The meaningful correlations between the zerosound modes and the stiffness of the nuclear equation of state (EOS) are uncovered in nuclear matter with the relativistic meanﬁeld theory. It is demonstrated that the highdensity zerosound modes merely exist in models with the stiff EOS. While the stiff EOS can be softened by including $\omega$meson selfinteractions (the $\omega^4$ term), the weakened coupling of the $\omega$meson selfinteractions reignites the zero sound at high density. These results suggest that the highdensity zerosound modes can be used to probe the stiffness of the EOS at supranormal densities. The implications and effects of zero sounds are also discussed in heavy ion collisions and neutron stars.
In April 2022, AGATA, the European Gearray at the forefront of gamma detection technology [1,2] was installed at LNL. Based on the new concept of gammaray tracking, it can identify the gamma interaction points (pulse shape analysis) and reconstruct via software the trajectories of the individual photons (gammaray tracking). Shortly thereafter a physics campaign has started using stable beams ranging from hydrogen to lead, delivered by the TandemALPIPIAVE accelerator complex at energies from 2025 MeV/u (lightest ions) to about 78 MeV/u (heaviest ions). In the first phase AGATA has been coupled to the PRISMA heavyion magnetic spectrometer to access the study of exotic nuclei produced in multinucleon transfer and fusionfission reactions. Different silicon detector arrays for light charged particles and ions have also been used. The physics cases under study involve shell evolution and configuration mixing in key regions of the nuclear chart, such the N=20 island of inversion and the nuclei around the doublymagic 78Ni, quadrupole and octupole shapes and collectivity across a wide range of nuclear masses, as well as measurements of astrophysical interest. Several Coulombexcitation experiments investigated shape coexistence along the Z=40 and Z=50 lines. In this presentation, the current status of the physics campaign ant its main results will be discussed.
References
[1] A. Akkoyun et al., NIM A 668, 26 (2012).
[2] J.J. ValienteDobón et al., NIM A 1049 168040 (2023).
The correlation between the charge radii differences in mirror nuclei pairs and the neutron skin thickness has been studied with the socalled finiterange effective interaction over a wide mass region. The so far precisely measured charge radii differences data within their experimental uncertainty ranges in $^{34}$Ar$^{34}$S, $^{36}$Ca$^{36}$S, $^{38}$Ca$^{38}$Ar and $^{54}$Ni$^{54}$Fe mirror pairs are used to ascertain an upper limit for the slope parameter of the nuclear symmetry energy
$L\approx$100 MeV. This limiting value of $L$ is found to be consistent with the upper bound of the NICER PSR J0704+6620 constraint at 1$\sigma$ level for the radius R$_{1.4}$ of the 1.4M$_\odot$ neutron
stars. The lower bound of the NICER $R_{1.4}$ data constraints the lower limit of $L\approx$70 MeV. Within the range for $L$=70100MeV the tidal deformability $\Lambda^{1.4}$ extracted from the GW170817 event at 2$\sigma$ level and the recent PREX2 and CREX data on the neutron skin thickness are discussed.
The understanding of the renormalization mechanisms of electroweak currents is nowadays a cornerstone of the nuclear structure research. It is motivated by the need of calculating reliable nuclear matrix elements for the neutrinoless double$\beta$ decay. Our approach to the problem is the realistic nuclear shell model. It provides a consistent framework to derive effective Hamiltonians and decay operators, the only parameter that is involved being the nuclear force one starts from.
We have successfully employed this approach to study the twoneutrino double$\beta$ decay of $^{48}$Ca, $^{76}$Ge, $^{82}$Se,$^{100}$Mo, $^{130}$Te, and $^{136}$Xe, and then extended it to predict the nuclear matrix elements of their neutrinoless double$\beta$ decay. Now, with the goal to further validate our approach in predicting $\beta$decay observables, I will present recent results on the sensitivity to the renormalization of shellmodel forbidden $\beta$decay operators describing the energy spectra of the emitted electrons of the secondforbidden $\beta$decays of $^{94}$Nb and $^{99}$Tc as well as the fourthforbidden $\beta$decays of $^{113}$Cd and $^{115}$In.
The rapid neutron capture process, or r process, is responsible for the production of half of the elements between iron and uranium found in nature. During the rprocess nucleosynthesis, several thousands of neutronrich nuclei are synthesized in few seconds, powering an electromagnetic transient known as kilonova. Since most of such exotic nuclei have never been experimentally observed due to their exceedingly short halflives, the estimation of abundances and kilonova light curves must rely upon the theoretical predictions of nuclear properties.
One of the most fundamental nuclear input in modelling the rprocess nucleosynthesis are nuclear masses. These determine the energy thresholds of nuclear reactions taking place at all stages of the evolution, shaping the abundance distribution and the kilonova light curve. In this talk, I will present a sensitivity study exploring the impact of masses on the rprocess nucleosynthesis. By identifying the nucleonic shell effects responsible for local changes in the binding energies, we isolate the most relevant features of nuclear mass surfaces in shaping abundance distributions and the kilonova light curves. These results provide a guidance to future experiments aimed to measure the properties of exotic nuclei in the region of the nuclear chart relevant for the r process.
Unitarity of the CabibboKobayashiMaskawa quark mixing matrix is a testable prediction of the Standard Model. The most precise constraint, the Cabibbo unitarity constraint, is currently provided by a combination of superallowed nuclear beta decays and kaon decays, testing SM self consistency at the 0.01% level. Recent improvements in the theory of SM radiative corrections to beta decays revealed an apparent 2.5$\sigma$ deficit, referred to as Cabibbo anomaly. I review the current status and main ingredients of this lowenergy puzzle and give an outlook to further developments and possible BSM explanations.
The BESIII experiment at the electronpositron collider BEPCII in Beijing (China) is successfully operating since 2008 and has collected large data samples in the taumass region, including the world’s largest data samples at the J/ψ and ψ 0 resonances. The recent observations of hyperon polarizations at BESIII opens a new window for testing CP violation, as it allows for simultaneous production and detection of hyperon and antihyperon pair twobody weak decays. The CPsymmetry tests can be performed in processes like e.g. $J/\psi\to\Lambda\bar{\Lambda}$, $J/\psi,\psi'\to\Sigma^+\bar{\Sigma}^$ and $J/\psi\to\Xi\bar{\Xi}$. For the $\Xi\to\Lambda\pi$ decay it is possible to perform two independent CP tests and determine the strong phase and weak phase difference.
Transverse momentum moments (TMMs) are defined as weighted integrals of transverse momentum distributions. They provide integral information about the hadron structure, such as average momentum, width, etc; and could be determined from the distributions and directly from the data. I review the theory and phenomenology of TMMs based on the recent N4LL analysis of DrellYan data.
The transport and spectral properties of heavy quarks and quarkonia in hot QCD matter are a central ingredient to describe heavyflavor observables in highenergy heavyion collisions. We discuss recent progress in evaluating these properties in a nonperturbative quantum manybody approach where the basic twobody interaction kernel is constrained by various quantities that can be computed with good precision in latticeQCD. In particular, we focus on recent analysis of Wilson line correlators and the nonperturbative calculation of quarkonium reaction rates, thereby also elaborating relations to the heavyquark diffusion coefficient.
Quantum manybody systems often stabilize by creating nonuniformity in them. Clustering in nuclei is one of good examples. Since the discovery of αdecay and later prediction/observation of the Hoyle state in 12 C, nuclear physicists have investigated mechanism how clusters occur in nuclei and how they play roles in synthesis of heavier elements. So far the scope of cluster research has been mainly limited to welldeveloped clusters in light nuclei and cluster formation in medium to heavy nuclei remains to be understood. We have started a new research project named the ONOKORO project where we comprehensively investigate clustering in mediumtoheavy mass nuclei using (p,pX) cluster knockout reactions under normal and inverse kinematics. The research is motivated by our previous study on α clustering in 112124 Sn conducted at Research Center for Nuclear Physics (RCNP), Osaka University [1]. Novel features of the ONOKORO project are to extend the knockoutreaction studies of clustering to 1) all the light clusters, deuteron, triton, 3 He, together with α, 2) nuclei in a long isotope chain by combining experiments for stable and unstable nuclei, 3) in a wide mass region up to A~220.
In July 2023 and April 2024, we have performed the first series of experiments for stable calcium isotopes at RCNP an obtained separation energy spectra. In parallel, we are preparing for experiments using RI beams at RIBF where a new detector telescope, TOGAXSI, specialized to inversekinematics cluster knockout experiments. In the seminar, I will discuss the physics background, research plans at RIBF, RCNP, and HIMAC facilities, and status of detector development for the inverse kinematics knockout experiments.
[1] J. Tanaka, Z.H. Yang et al., Science 371, 260 (2021)
[2] J. Tanaka, R. Tsuji et al., Nucl. Instrum. Methods Phys. Res. B 542, 4 (2023).
Exploring the lightquark mass dependence of nearthreshold exotic states provides insights into their internal structure. In this talk, we introduce a novel approach based on chiral effective field theory to extract the properties of such states from lattice energy levels [1]. This approach benefits from the incorporation of lefthand cuts originating from longrange interactions, thereby extending beyond the wellknown Lüscher method. Also, the presence of the lefthand cuts in the vicinity of the threshold restricts the effective range expansion, commonly used for analyzing infinite volume phase shifts, to a very narrow energy range [2].
The proposed approach is applied to systematically extract, for the first time, the properties of the Tcc state, particularly the pole position and the lowenergy parameters, from recent lattice data for DD* scattering at mpi=280 MeV [3], accounting for the lefthand cut contribution from the onepion exchange [1]. The onepion exchange is shown to have a significant impact on Swave and Pwave phase shifts as well as the Tcc pole position. Consequences for the structure of the Tcc are discussed.
[1] L.~Meng, V.~Baru, E.~Epelbaum, A.~A.~Filin and A.~M.~Gasparyan,
``Solving the lefthand cut problem in lattice QCD: $T_{cc}(3875)^+$ from finite volume energy levels,'' [arXiv:2312.01930 [heplat]], accepted for publication in Physics Review D (letter).
[2] M.~L.~Du, A.~Filin, V.~Baru, X.~K.~Dong, E.~Epelbaum, F.~K.~Guo, C.~Hanhart, A.~Nefediev, J.~Nieves and Q.~Wang,
``Role of LeftHand Cut Contributions on Pole Extractions from Lattice Data: Case Study for Tcc(3875)+,'' Phys. Rev. Lett. \textbf{131} (2023), 131903
[3] M.~Padmanath and S.~Prelovsek, ``Signature of a Doubly Charm Tetraquark Pole in DD* Scattering on the Lattice,'' Phys. Rev. Lett. \textbf{129} (2022), 032002
We recall that the chiral unitary approach for the interaction of
pseudoscalar mesons with the baryons of the decuplet predicts two states
for the $\Xi(1820)$ resonance, one with a narrow width and the other one
with a large width. We contrast this fact with the recent BESIII
measurement of the $K^ \Lambda$ mass distribution in the $\psi(3686)$ decay to
$K^ \Lambda \bar\Xi^+ $, which demands a width much larger than the average
of the PDG, and show how the consideration of the two $\Xi(1820)$ states
provides a natural explanation to this apparent contradiction.
We investigated mesonbaryon scattering using timeorder perturbation theory based on covariant chiral effective field theory. Renormalized scattering amplitudes were obtained by solving the integral equations with the full offshell dependence of effective potentials and applying subtractive renormalization. Our formalism has been successfully applied to the pionnucleon scattering at leading order and extended to mesonbaryon scattering in the $S=1$ sector. By solving the coupledchannel integral equations, we obtained the twopole structure of the $\Lambda(1405)$ resonance. Confronting the recent lattice QCD study, we investigated the lightquark mass dependence of $\Lambda(1405)$ two poles. Furthermore, we would like to present the preliminary results of the ongoing work at the nexttoleading order on mesonbaryon interactions.
When two particles form a nearly resonant bound state due to shortrange attractive forces, an effective longrange threebody emerges giving rise to an infinite number of threebody bound states with a discrete scale invariance. This phenomena, called Efimov effect, was first described in the 1970's by V. Efimov [1]. The Efimov effect has been mostly studied in atomic physics, due to its experimental observation in Cesium atoms in 2006 [2]. However, its relevance has also been explored in nuclear physics, e.g., in the $^{12}C$ three$\alpha$ structure, the triton formation or the nuclear halo of $^{14}Be$, $^{22}C$ and $^{20}C$ nuclei.
The existence of threebody bound states and its lowenergy universality in the charm and bottom sectors has been explored in the recent literature, specially since the discovery of the $X(3872)$ state, a looselybound $D^{*\,0}\bar D^0$+h.c. molecule with quantum numbers $J^{PC}=1^{++}$. The properties of the $X(3872)$, unfortunately, rule out the existence of the Efimov effect [3]. However, the recent discovery in 2021 of the $T_{cc}^+$ [4] can renew this interest.
In this talk I will analyze the $D^*D^*D^*$ system in the $J^P=0^$ sector with $I=\frac{1}{2}$, assuming that the isoscalar heavy partner of the $T_{cc}^+$, dubbed $T_{cc}^*$, exists close and below the $D^*D^*$ threshold. I find that $(I)J^P=(\frac{1}{2})0^$ threebody bound states can be formed, with properties that suggest that the Efimov effect can be realised for reasonable values of the molecular probability and binding energy of the $T_{cc}^*$ [5].
[1] V. Efimov, Phys. Lett. B 33 (1970), 563564.
[2] T. Kraemer, Nature 440, Issue 7082, pp. 315318 (2006).
[3] E. Braaten and M. Kusunoki, Phys. Rev. D 69 (2004), 074005.
[4] R. Aaij et al. [LHCb], Nature Phys. 18 (2022) no.7, 751754.
[5] P.G. Ortega, arXiv:2403.10244 [hepph].
The Belle and Belle$~$II experiments have collected a $1.4~\mathrm{ab}^{1}$ sample of $e^+e^$ collision data at centreofmass energies near the $\Upsilon(nS)$ resonances. These data include a 19.2$~$fb$^{1}$ sample collected near the $\Upsilon(10753)$ resonance to probe its potentially exotic nature. We present several results related to the following processes: $e^+e\to \Upsilon(nS)\eta$, $e^+e\to \gamma X_b(\chi_{bJ}\pi^+\pi^)$, $e^+ e^\to h_b(1P)\eta$ and $e^+e^\to\chi_{bJ}(1P)\omega$. The last analysis also includes data samples collected by Belle at similar centreofmass energies. In addition, we present Belle measurements of the $B^{0}$ and $B^+$ meson mass difference, a pentaquark search in $\Upsilon(1S)$ and $\Upsilon(2S)$ decays, as well as studies of $h_b(2P)$ decays to the $\eta \Upsilon(1S)$ and $\chi_{bJ}\gamma$ final states.
We calculate the Next to Leading Order corrections to inclusive production of a quarkantiquark pair in a strong color field. We show that all possible divergences either cancel or are absorbed into evolution of physical quantities. We show how our results can be used for precision studies of quark production in ultraperipheral heavy ion collisions.
Nonperturbative resummation at finite temperature via the Gribov gluon propagator was proposed by D. Zwanziger in 2005 [1]. Later, in 2013, it was used by K. Fukushima and N. Su [2] to study gluon thermodynamics. In 2015, N. Su and T. Tywoniuk showed that a novel massless excitation is ascribable to the magnetic scale in quark dispersion relations.
We recently used the nonperturbative resummation via the Gribov gluon propagator to calculate various quantities relevant to hot and dense nuclear matter. We have studied share and bulk viscosities [4], heavy quark diffusion coefficient[5], meson screening mass[6], heavy quarkonium potential[7], et. al. In all the cases, we get an improvement over the perturbative result near the transition temperature. In this talk, I will discuss the recent findings we obtained using the nonperturbative resummation.
Ref:
1. Phys.Rev.D 73 (2006) 094504; Phys.Rev.Lett. 94 (2005) 182301
2. Phys.Rev.D 88 (2013) 076008
3. Phys.Rev.Lett. 114 (2015) 16, 161601
4. Phys.Lett.B 811 (2020) 135936; arXiv:2401.08384
5. Phys.Lett.B 838 (2023) 137714
6. Phys.Lett.B 845 (2023) 138143
7. arXiv: 2305.16250[to appear in EPJC]
We solve a Boltzmann equation that describes the dynamics of coupled massless quark and gluon fluids undergoing transversally homogeneous boostinvariant expansion. The quark and gluon components are taken to have the same dynamical anisotropy parameter, but we introduce a fugacity parameter that allows quarks to be out of chemical equilibrium, as expected right after the formation of the QGP in heavyion collisions. To describe the different collision rates for quarks and gluons we introduce different relaxation times for quarks and gluons, which are related via Casimir scaling. Based on these assumptions, we derive coupled Boltzmann equations that are obeyed by all moments of the distribution functions. We find that both early and latetime attractors exist for all moments of the distribution functions with the only exception for lowerorder moments, whose behavior is not universal during the early stages of the longitudinal expansion. This attractor emerges long before the system reaches the regime where hydrodynamic approximations apply. In addition, we discuss how the shear viscous corrections and scaled entropy density of the fluid mixture evolve and consider the properties of their respective attractors. Finally, the entropy production is also investigated for different initial values of momentum anisotropy and quark abundance.
We derive the equations of motion of relativistic magnetohydrodynamics, as well as microscopic expressions for all of its transport coefficients, from the Boltzmann equation using the method of moments. In contrast to reference Phys.~Rev.~D 98(7) 2018, where a single component gas was considered, we perform our derivation for a locally neutral fluid composed of two massless particle species with opposite charges. We demonstrate that the magnetohydrodynamical equations of motion become dramatically different for this more realistic system. The shearstress tensor no longer obeys a single differential equation; it breaks into three nondegenerate components with respect to the magnetic field, each evolving according to different dynamical equations. For large magnetic fields, we further show that the solution of this theory displays oscillatory behaviour that can no longer be described by an IsraelStewartlike theory. Finally, we investigate the derived equations in a Bjorken flow scenario.
Measurements at the LHC have provided evidence for collective behavior in highmultiplicity protonproton (pp) and protonlead (pPb) collisions through multiparticle correlation techniques. To investigate detailed properties of this collectivity, a comprehensive study of differential Fourier coefficients ($v_{n}$) in particle transverse momentum ($p_\mathrm{T}$) and event multiplicity is presented in pPb collisions recorded by the CMS experiment at a nucleonnucleon centerofmass energy $\sqrt{s_{_{\mathrm{NN}}}} = 8.16$ TeV. In particular, new measurements of $p_\mathrm{T}$differential multiparticle cumulants using the subevent cumulant method in distinct subevent regions are presented. Relative to past CMS measurements, the new study probes an extended phase space region up to a high particle $p_\mathrm{T}$, putting the observation of nonzero high$p_\mathrm{T}$ $v_{2}$ in a smallsized medium into stringent tests.
In this work, we perform a Bayesian analysis putting together the available knowledge from the nuclear physics experiments and astrophysical observations to explore the equation of state of supranuclear matter. In particular, we employ a relativistic metamodeling technique to nuclear matter to cover the uncertainties in the parameter space of the saturation properties of nuclear matter, both in the isoscalar and isovector sectors. Then, we investigate if it is possible to reconcile the inferred values of those quantities from observational data with the values obtained from nuclear experiments and compute a joint posterior of these quantities incorporating all the available knowledge. We further probe the fractions of different particle species that the interior of a neutron star may contain, particularly the proton fraction in the core and the consequences of the allowed compositions within our metamodel. We also incorporate the possible emergence of hyperons in the system and the number of ways that the nucleonic metamodel can accommodate hyperons in the neutron star matter. Finally, we calculate the strangeness content in the star and discuss its observational implications.
We have attempted to mitigate the challenge of connecting the neutron star (NS) properties with the nuclear matter parameters that describe equations of state (EOSs). The efforts to correlate various neutron star properties with individual nuclear matter parameters have been inconclusive.
A Principal Component Analysis is employed as a tool to uncover the connection between multiple nuclear matter parameters and the tidal deformability as well as the radius of neutron stars within the mass range of $1.21.8M_\odot$. The essential EOSs for neutron star matter at low densities have been derived using both uncorrelated uniform distributions and minimally constrained joint posterior distributions of nuclear matter parameters. For higher densities ($\rho > 0.32$fm$^{3}$), the EOSs have been established through a suitable parameterization of the speed of sound, which consistently maintains causality and gradually approaches the conformal limit. Our analysis reveals that in order to account for over 90\% of the variability in NS properties, it is crucial to consider two or more principal components, emphasizing the significance of employing multivariate analysis. To explain the variability in tidal deformability needs a greater number of principal components compared to those for the radius at a given NS mass. The contributions from isovector nuclear matter parameters to the tidal deformability and radius of NS decrease by $\sim$ 25\% with the increase in mass of NS from 1.2$M_\odot$ to 1.8$M_\odot$.
In our work we present general predictions for the static observables of neutron stars (NSs) under the hypothesis of a purely nucleonic composition of the ultradense baryonic matter, using Bayesian inference on a very large parameter space conditioned by both astrophysical and nuclear physics constraints.
The equation of states are obtained using a unified approach of the NS core and inner crust within a fully covariant treatment based on a relativistic meanfield Lagrangian density with density dependent couplings. The posterior distributions are well compatible with the ones obtained by semiagnostic metamodelling techniques based on nonrelativistic functionals, that span a similar portion of the parameter space in terms of nuclear matter parameters, and we confirm that the hypothesis of a purely nucleonic composition is compatible with all the present observations.
We additionally show that present observations do not exclude the existence of very massive neutron stars with mass compatible with the lighter partner of the gravitational event GW190814 measured by the LIGOVirgo collaboration.
Some selected representative models, that respect well all the constraints taken into account in this study, and approximately cover the residual uncertainty in our posterior distributions, will be uploaded in the CompOSE database for use by the community.
The longsought equation of state of hadronic matter across a wide range of densities and temperatures, based on first principles with quarks and gluons i.e. quantum chromodynamics remains one of the key issues in physics. Over the past decade, a widely rich variety of data pouring in from laboratory experiments as well as astrophysical observations, including the detection of gravitational waves from binary neutron star mergers and the observations of a subsequent electromagnetic signal have raised new challenges. Simulations of these latter events based on numerical solutions of the hydrodynamic equations in General Relativity require the knowledge of the EoS of matter. Remarkable progress in the chiral effective field theory (χEFT) in recent years has started to provide some realistic answers. However, the perturbative momentum expansion techniques applied in χEFT theory break down at high densities that are relevant for the matter in these extreme astrophysical environments. Moreover, this approach is not computationally tractable for low density matter where clusters are present. The density functional theory has proven to be one of the most viable approaches to achieve these goals.
In this contribution, I will start with an overview of different types of equation of state modelling in the Bayesian formalism, to demonstrate the impact of different experimental and observational constraints. Further, I will present equations of state at finite temperature obtained with BrusselsSkyrmeonaGrid (BSkG) energy density functionals developed at Brussels, which are unified across the crust and core of the neutron star environment. These models have demonstrated remarkable accuracy over the whole nuclear chart on the masses, and fission barriers of nuclei, but at the same time they also satisfy recent astrophysical constraints. I will also outline the impact of our calculations at finite temperatures on the composition of the crust in the neutron stars. Our future goal is to apply these equations of state in the simulation of binary neutron star mergers.
"Solving the quantum manybody problem involves nontrivial challenges arising from the exponential growth of the Hilbert space dimension, which restricts the applicability of numerically exact techniques to relatively small systems. I will discuss how variational Monte Carlo methods, based on artificial neural networks, can provide a systematically improvable solution to the quantum manybody problem with a polynomial cost in the number of interacting particles. My focus will be on nuclear systems, including finite nuclei and neutronstar matter, but I will also present applications to condensedmatter systems, such as cold Fermi gases near the unitary limit. Finally, I will provide perspectives on accessing the realtime dynamics of quantum manybody systems.
Ab initio is the expression used to refer to the subset of techniques in nuclear structure that perform calculations from "first principles". While being the most accurate approach in describing atomic nuclei to the date, it is still not used in many fields of nuclear physics due to its high computational cost.
Recently, a method dubbed Neural Quantum States was proposed, and there are indications that it might be able to surpass the current stateoftheart ab initio calculations. The idea is simple: one uses an artificial neural network as a wave function ansatz in a variational setting, and then the energy expectation is set as the loss function to minimise. Not only are neural networks, if sufficiently big, universal function approximators, but they also seem to be able to efficiently compress all the information in a Hilbert space.
In this talk I will present this method in some detail, and I will also illustrate both the achievements and the practical challenges that we are facing when using it to describe nuclei, namely numerical optimisation and neural network architecture. I will place a special focus on how to embed physical symmetries in neural network ansätze, which is my current line of research.
Quantum entanglement offers a unique perspective into the underlying structure of stronglycorrelated systems such as atomic nuclei. Using different entanglement metrics on equipartitions of the valence space, we analyze the structure of light and mediummass berillyum, oxygen, neon and calcium isotopes within the nuclear shell model, and we identify modeentanglement patterns related to the energy, angular momentum and isospin of the nuclear singleparticle orbitals. We observe that the singleorbital entanglement is directly related to the number of valence nucleons and the energy structure of the shell, while the mutual information highlights signatures of proton–proton and neutron–neutron pairing, as well as nuclear deformation. Proton and neutron orbitals are weakly entangled by all measures, which provides a guide for designing more efficient quantum algorithms for the noisy intermediatescale quantum (NISQ) era. For some of the studied examples, we show how to exploit this advantage by simulating an AdaptVQE with circuits of fewer qubits than would be needed conventionally. This technique, known as entanglement forging, can make it possible for NISQ devices to simulate large nuclei in this regime.
This study presents a simulated quantum computing approach for the investigation into the shellmodel energy levels of $^{58}$Ni through the application of the variational eigensolver (VQE) method in combination with a problemspecific ansatz. The primary objective is to achieve a fully accurate lowlying energy spectrum of $^{58}$Ni. In this study, we utilized two distinct shell model spaces: $fp$ and $fpg$. The $fp$ model space comprises the orbitals $1p_{3/2}$, $0f_{5/2}$, and $1p_{1/2}$ beyond the $^{56}$Ni core, represented using 12 qubits (one per orbital). Extending our analysis, we delved into the broader model space $fpg$, which includes the orbitals mentioned earlier along with the $0g_{9/2}$ orbital above the $^{56}$Ni core, utilizing 22 qubits for its representation. The chosen isotope, $^{58}$Ni is particularly interesting in nuclear physics through its role in astrophysical reactions while also being a simple but nottrivial nucleus for shellmodel study, it being two particles outside a closed shell. The Hamiltonian is based on shellmodel interaction (JUN45). Our ansatz, along with the VQE method are able to reproduce exact energy values for the ground state and first and second excited states for 12 qubits. With 22 qubits, the ansatz accurately reproduces the ground state and second excited state energy values. However, there are disparities between the obtained results and the shellmodel result for the first excited state with the prepared ansatz. For the first excited state, using 22 qubits, efforts are underway to improve and finetune the ansatz. We compare a classical shell model code, the values obtained by diagonalization of the Hamiltonian after qubit mapping, and a noiseless simulated ansatz+VQE simulation. The exact agreement between classical and qubitmapped diagonalization shows the correctness of our method, and the high accuracy of the simulation means that the ansatz is suitable to allow a full reconstruction of the full nuclear wave function.
There is an increasing interest to develop quantum circuits capable of performing manybody quantum simulation motivated by their scaling advantages against classical devices. We present an analysis of the performance of various Variational Quantum Eigensolvers methods for the 6Li nucleus in the shell model framework. In particular, our work is focused on the construction of efficient Unitary Coupled Cluster ansatzë variations, with special interest in comparing their performance with the ADAPT method. By using a small nucleus as the 6Li, we are able to simulate these variational methods, in order to benchmark the resources needed for convergence.
The SIDDHARTA2 experiment, conducted at the INFNLNF DAΦNE collider, is currently engaged in a data collection campaign aimed at achieving the firstever measurement of the stronginteractioninduced shift and width on the 1s level of kaonic deuterium. Exploiting the superior quality of the lowenergy kaon beam provided by the DAΦNE collider in Frascati, Italy, and employing stateoftheart Xray detectors such as Silicon Drift Detectors (SDDs), High Purity Germanium (HPGe), and CadmiumZincTelluride (CdZnTe) devices, the SIDDHARTA2 Collaboration is performing simultaneousparallel measurements on various kaonic atoms. These efforts are anticipated to have significant implications for the lowenergy strangeness sector.
This contribution will outline the physics motivation, describe the experimental apparatus, highlight several noteworthy results obtained so far with different kaonic atoms, provide an update on the current status of the kaonic deuterium measurement, and offer an overview of the forthcoming kaonic atom measurements planned by the collaboration.
It has been argued that the formation of a molecularlike quasibound state, $\Lambda(1405)$, arises from the strong attraction between $\overline{K}N$ with isospin I = 0 channel. Furthermore, its strong attraction suggests the existence of kaonic nuclei in a threebody system, $K^{}pp$, as well as in more complex manybody systems.
Some calculations suggest existence of various types of manybody systems involving Kaon and nucleons. However, apart from the observation of the $K^{}pp$ threebody system[1][2], there have been few clear confirmations for the existence of Kaonic nuclei. Therefore, it is crucial to systematically investigate Kaonic nuclei across a wide range of mass numbers not only for understanding $\overline{K}N$ interactions but also for obtaining information on the presence or absence of $\overline{K}$ within the inner core region of neutron stars.
The JPARC E05 experiment studied the interaction between $\overline{K}$ and a residual nucleus by measuring an inclusive $^{12} \text{C} (K^{}, p)$ spectrum. From the analysis, the depths of both the real and imaginary parts of the $\overline{K}$nucleus optical potential were obtained to be (80, 40) [MeV] by fitting the shallow bound region with a theoretically calculated spectrum[3]. In addition, a significant event excess was observed in the spectrum in the deeply bound region around 90 MeV in the $\overline{K}$ binding energy. That excess fits well with a BreitWigner function whose binding energy is 90 MeV and width is 100 MeV, suggesting possible contribution from production of $\overline{K}NN$ or a bound state between an excited hyperon $(Y^{＊})$ and a nucleus.
To investigate the reason behind the excess event, we conducted a new experiment called E42[4]. This experiment used the same reaction, $^{12} \text{C} (K^{}, p)$, as a byproduct of the Hdibaryon search experiment. We used a GEMbased Time Projection Chamber, HypTPC, installed around the target to measure the decaycharged particles during this experiment. This measurement technique helped improve the signaltonoise ratio and allowed us to detect the $Y^{＊}$ nuclear state as a clear bump if it exists.
In this talk, we will summarize the E05 results and report preliminary results of the inclusive $^{12}\text{C}(K^{}, p)$ spectrum and the exclusive analysis using the information on particle identification with HypTPC.
Reference
[1] S. Ajimura et al. Phys. Let. B 789 (2019) 620625
[2] T. Yamaga et al. Phys. Rev. C 102, 044002 (2020)
[3] Y. Ichikawa et al., PTEP 2020, 123D01 (2020)
[4] J.K. Ahn et al., the proposal of JPARC E42 experiment, Search for HDibaryon with a Large Acceptance Hyperon Spectrometer
It is important to investigate the inmedium quark condensates to understand the mechanism of the spontaneous breaking of chiral symmetry. The up and down quark condensates in nuclear medium are studied by pionic atoms and low energy pion nucleus scattering. It is found that the magnitude of the ud quark condensates may be reduced by 30% at the nuclear saturation density. This is known as partial restoration of chiral symmetry in nuclear medium. For a systematic study of partial restoration of chiral symmetry, it is interesting to see how the strange quark condensate behaves in nuclear matter. The chiral ward identity connects the inmedium quark condensate to the soft limit value of a correlation function of the pseudoscalar fields evaluated in nuclear medium. For the strange quark condensate, one considers the correlation function of the pseudoscalar fields with strangeness. The correlation function describes inmedium propagation of kaon and it is obtained phenomenologically by kaonnucleon scattering in the low density approximation. In this talk we describe the kaonnucleon scattering amplitude in chiral perturbation theory and its low energy constants are determined by existent K+N scattering data. Performing analytic continuation of the scattering amplitude obtained by chiral perturbation theory, we can take soft limit of the scattering amplitude. With this amplitude, we evaluate the inmedium strange quark condensate based on hadron phenomenology. We also discuss a possible broad resonance with S=+1 appearing in the KN scattering with I=0 around W=1650 MeV.
Hypernuclei provide important information to constrain the hyperonnucleon (YN) and threebaryon (YNN) interactions. In this contribution, we will discuss our recent results obtained using chiral YN [1,2] and chiral YNN interactions for light hypernuclei up to $A=8$.
We use the hypernuclei data to determine the chargesymmetry breaking (CSB) of YN interactions and for exploring the results using $A=7$ and $A=8$ isospin multiplets of hypernuclei [3,4]. We then employ the results of different chiral orders to reliably estimate the theoretical uncertainty [5]. Finally, we use the separation energies of light hypernuclei to pin down the leading chiral YNN interaction.
[1] J.Haidenbauer, U.G.Meißner and A.Nogga, Eur. Phys. J. A 56 (2020) no.3, 91 [arXiv:1906.11681 [nuclth]].
[2] J.Haidenbauer, U.G.Meißner, A.Nogga and H.Le, Eur. Phys. J. A 59 (2023), 63 [arXiv:2301.00722 [nuclth]].
[3] J.Haidenbauer, U.G.Meißner and A.Nogga, Few Body Syst. 62 (2021), 105 [arXiv:2107.01134 [nuclth]].
[4] H.Le, J.Haidenbauer, U.G.Meißner and A.Nogga, Phys. Rev. C 107 (2023), 024002 [arXiv:2210.03387 [nuclth]].
[5] H.Le, J.Haidenbauer, U.G.Meißner and A.Nogga,Eur. Phys. J. A 60 (2024), 3 [arXiv:2308.01756 [nuclth]].
The possible existence of deeplybound $\bar K$nuclear bound states (kaonic nuclei) has been widely discussed as a consequence of the strongly attractive $\bar K N$ interaction in I = 0 channels. The investigation of kaonic nuclei can provide unique information about the $\bar K N$ interaction below the threshold, which is still not fully understood.
For the simplest kaonic nucleus, $\bar KNN$, we performed an experimental search using the inflight $^3$He$( K^, n)$ reactions at 1 GeV/$c$ (JPARC E15). With the $\Lambda pn$ final state reconstructed, we observed a significant peak below the $K^pp$ massthreshold in the $\Lambda p$ invariantmass spectrum, which can be interpreted as the ``$K^pp$’’ bound state.
To further understand the kaonic nuclei, we have proposed and prepared the E80 experiment to precisely measure the $\bar K NNN$ system as a first step toward the comprehensive study of the light kaonic nuclei from the “$\bar K N$” (=$\Lambda$(1405)) to“$\bar K NNNN$.” Through the experiments and detailed theoretical calculations, we will unravel the nature of the kaonic nuclei from the property changes depending on the mass number $A$.
We will discuss the $\bar KNN$ bound state observed at JPARC E15 and the future prospects of light kaonic nucleus studies at JPARC starting with the E80 experiment.
A search for the $H$dibaryon has been conducted at JPARC using a 1.8 GeV/c $K^$ beam, in June 2021. The E42 experiment was designed to maximize sensitivity from a loosely bound $H$ to resonances near $\Lambda\Lambda$ and $\Xi^p$ thresholds with the Hyperon Spectrometer. A timeprojection chamber (HypTPC) reconstructs all charged particles' trajectories that emerged from the $^{12}$C$(K^, K^+)X$ reaction. We observed thousands of $\Lambda\Lambda$ events, which are two orders of magnitude more than ever. We believe the observation of such large statistics $\Lambda\Lambda$ events will shed light on the Hdibaryon search. We will present the E42 apparatus and analysis progress toward the $H$dibaryon search and outline preliminary results on $\Lambda\Lambda$ production in the $^{12}$C$(K^, K^+)X$ reaction.
The existence of exotic multiquark states beyond the conventional valence three quark and quarkantiquark systems has been unambiguously confirmed in the heavy quark sectors. Such states could manifest as single colour bound objects, or evolve from mesonbaryon and mesonmeson interactions, creating molecular like systems and rescattering effects near production thresholds. Equivalent structures may be evidenced in the light, $uds$ sector. The BGOOD photoproduction experiment at ELSA is ideal to study spatially extended, molecularlike structure which may manifest in reaction mechanisms. BGOOD is comprised of a central calorimeter for neutral meson momentum reconstruction and complemented by a magnetic spectrometer in forward directions for charged particle identification.
Our published results in the strangeness sector may suggest a dominant role of mesonbaryon dynamics which has an equivalence to the $P_C$ states in the charmed sector. This includes structure in $K^0\Sigma^0$ and $K^+(\Lambda(1405)\rightarrow \pi^0\Sigma^0)$ photoproduction at the $K^*Y$ thresholds having a direct analogue to the $P_C(4457)$ at the $\Sigma_C \bar{D}^*$ threshold.
In the nonstrange baryonbaryon sector, coherent meson photoproduction off the deuteron enables access to proposed dibaryon states, including the recently discovered candidate, $d^*(2380)$. Our measured differential cross sections at forward angles challenge conventional descriptions of coherent photoproduction, which should be suppressed due to the large momentum transferred to the deuteron.
Supported by DFG projects 388979758/405882627 and the European Union’s Horizon 2020 programme, grant 824093.
I report the results of the Regge model study of the spin density matrix elements (SDMEs) of the $\Delta(1232)$ in the photoproduction reaction ${\vec\gamma} p \to X^\Delta^{++}$ where $X\in(\pi,b_1)$. These reactions are being studied by GlueX in its ongoing efforts to understand the spectrum the light hybrid mesons. The intensity profile of the photoproduction of resonance(s) from a polarized photon is governed by the SDMEs of the resonance(s) produced. While the line shapes provide information about the decay of the unstable states, the SDMEs tell us about their production mechanism. I present the results of the ongoing efforts at the JPAC to model the photoproduction of mesonic resonances along with the $\Delta$, the insights derived from the properties of the SDMEs, and briefly discuss their implications for higher spin states.
In addition to conventional hadrons, such as baryons and mesons, quantum chromodynamics predict the existence of other hadronic states based on the principle of colour confinement. Among these, hybrid states are particularly intriguing. They arise from excitation in the gluonic field or, in a constituent approach, from the inclusion of a constituent gluon within the system. In recent years, both theoretical and experimental efforts have been dedicated to the study of hybrid mesons. Their identification seems, at first sight, easier since some $J^{PC}$ quantum numbers are forbidden in a $q\bar{q}$ configuration but allowed for $q\bar{q}g$. On the other hand, hybrid baryons do not have such "smoking gun" signature since all quantum numbers $J^P$ can be populated by conventional $qqq$ configuration. On the theory side, hybrid baryons have been studied within the framework of the MIT bag model, flux tube model, QCD sum rules, large$N$ QCD and lattice QCD. Although these models predict the existence of hybrid baryons, their predictions for the masses and structures differ considerably from each other. On the experimental side, significant efforts are underway at the Jefferson Laboratory to identify these particles.
In this presentation, we propose a constituent model for describing hybrid baryons with heavy quarks. First, the flavourspincolour wavefunctions of the core of quarks are computed based on the Pauli exclusion principle. Then, the spin of the core of quarks is coupled to the helicity of the gluon by using the twobody helicity formalism of Jacob and Wick, leading to a series of helicity states with fixed $J^P$ quantum numbers. Eventually, the spectrum of the system is computed by the help of the method of the envelope theory, which was already used in the past for studying conventional baryons and hybrid mesons, with conclusive results.
We present a simple holographic QCD model for nucleons and vector mesons. The model can be thought of a consistent embedding of soft wall models in Einsteindilaton gravity and it leads to hadronic correlators compatible with QCD in the large N limit. We compare our results for the hadronic masses and decay constants against previous models and available experimental data.
Reference: ePrint: 2402.17950 [hepph]
We present a first calculation of the unpolarized proton's isovector transversemomentumdependent parton distribution functions (TMDPDFs) from lattice QCD, which are essential to predict observables of multiscale, semiinclusive processes in the standard model. We use a $N_f=2+1+1$ MILC ensemble with valence clover fermions on a highly improved staggered quark sea (HISQ) to compute the quark momentum distributions in largemomentum protons on the lattice. The stateoftheart techniques in renormalization and extrapolation in the correlation distance on the lattice are adopted. The oneloop contributions in the perturbative matching kernel to the lightcone TMDPDFs are taken into account, and the dependence on the pion mass and hadron momentum is explored.
Our results are qualitatively comparable with phenomenological TMDPDFs, which provide an opportunity to predict high energy scatterings from the first principles.
The photoproduction of vector mesons off the proton has long been established as an important tool to access the gluon content of the nucleon. In particular, the photoproduction of J/$\psi$ near the threshold energy has been related to the Gravitational Form Factors of the gluons which provide information about the mass and the force distributions in the nucleon. In this talk, I will present results on the nearthreshold photoproduction of J/$\psi$ using data taken in 2018 and 2019 by the CLAS12 detector at Jefferson Lab, with an electron beam impinging on a liquidhydrogen target. This measurement is expected to provide direct insight on the gluons distribution inside the proton.
Measuring Deeply Virtual Compton Scattering (DVCS) is crucial to the study of Generalised Parton Distributions (GPDs). GPDs provide a description in 3D of the position and momentum of quarks and gluons inside the nucleon, which is essential to understand how its global properties emerge.
The extraction of GPDs necessitates high precision measurements of multiple observables on a wide kinematic range. The CLAS12 experiment at JLab uses the upgraded 10.5 GeV polarised electron beam, allowing for the exploration of a broad kinematic range in the valence region with high statistics.
I will present preliminary DVCS spin asymmetry results from the first longitudinally polarised proton target experiment at CLAS12.
In this study, we present an updated determination of the generalized parton distributions (GPDs) at zero skewness through the global analysis of the experimental data of various physical observables. These data encompass nucleon electromagnetic form factors (FFs), proton axial FFs, nucleon charge and magnetic radii, the elastic antineutrinoproton scattering cross section, wideangle Compton scattering (WACS) cross section, and the nucleon electromagnetic transition FFs to Delta baryon. We discuss the implications of the extracted GPDs for enhancing our understanding of hadron structure.
Last years have brought a breakthrough in the lattice calculations of xdependent partonic distributions, such as generalized parton distributions (GPDs). The recent progress for the latter is related to the use of asymmetric frames of reference. This allows for simultaneous access to several values of the momentum transfer, significantly enhancing the prospects of fully mapping the multidimensional dependence of GPDs. We review this progress in numerical investigations of all leadingtwist as well as some examples of twist3 GPDs.
We analyze different problems related to the physics of hadrons under extreme conditions of temperature and chemical potentials. On the one hand, we show that the thermal resonances $f_0(500)$ and $K^∗_0(700)$, generated in the framework of Unitarized Chiral Perturbation Theory $\pi\pi$ and $K\pi$ scattering at finite temperature, play an essential role with respect to chiral and $U(1)_A$ restoration. On the other hand, a lowenergy effective lagrangian is constructed within ChPT at nonzero chemical potential, considering nonzero isospin and axial chemical potentials.
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We compute the vacuum energy density as a function of the quark condensate in the interacting instanton liquid model (IILM) and examine a pattern of dynamical chiral symmetry breaking from the behavior of the vacuum energy density at the origin. This evaluation is performed by using a numerical simulation of the IILM. We find that chiral symmetry is broken in the U(1)_A anomaly assisted way in the IILM with threeflavor dynamical quarks. We also find the instantonquark interaction included in the IILM plays a crucial role for the symmetry breaking by comparing the full and the quenched IILM calculations.
We study the effect of a finite volume for pionpion scattering over energy levels and physical
observables such as the phaseshift or pion mass. The method to determine the energy levels is done
using a finite set of cubic harmonics or the matrices which represents the Irreps properly, which
expands our Inverse Amplitude Method, (as well we apply the method already in the known Bether
Salpeter equations  BSE ) over a set of irreducible groups of rotations from the octahedral group,
giving us a forward classification of energy levels, independently of whether we are including uand
tloops. On the other hand, the study of finite corrections of pion mass and phaseshift is
already done, looking a dependence with the size of the box (L). We expect that our results will help
to optimize the process of determination of energy levels and phaseshifts with higher accuracy,
including multiple loops.
The mass of the $\eta^{\prime}$ meson is notably large compared to other members of the light pseudoscalar meson nonet. The origin of the large mass is considered to be attributed to the axial U(1) anomaly and the spontaneous breaking of chiral symmetry in the QCD vacuum. In nuclear matter, various theoretical models predict a mass reduction of $\eta^{\prime}$ meson ranging from 37 to 150 MeV/$c^2$. Such a mass reduction leads to an attractive interaction with nuclei, suggesting the existence of a bound state between $\eta^{\prime}$ mesons and nuclei, $\eta^{\prime}$mesic nuclei.
To search for $\eta^{\prime}$mesic nuclei, we conducted missingmass spectroscopy in the $^{12}\mathrm{C}(p,d)$ reaction with simultaneous measurements of decay products of $\eta^{\prime}$mesic nuclei at the fragment separator (FRS) at GSI in 2022 February. Here, forwardgoing deuterons were detected with the FRS to obtain the missingmass spectrum. The WASA central detector was installed at the central focal plane of the FRS to perform coincidence measurements of deuterons with backward protons originating from the decay of $\eta^{\prime}$mesic nuclei.
The presentation will provide relevant details of the experiment and the status of the data analysis.
The diffusion of heavy quarks (HQ) in the quarkgluon plasma (QGP) produced in ultrarelativistic heavyion collisions has been a successful probe of the HotQCD matter, allowing to identify a marked nonperturbative dynamics and inferring a spatial diffusion $D_s$ coefficient in agreement with first quenched lattice QCD data, even if within still significant uncertainties.
I will review some recent progress in the theoretical developments of heavyquark interactions in the QGP and the open issues in comparing the phenomenological determination of $D_s(T)$ and more recent lattice QCD data (supplemented by NREFT) in nonquenched approximation. I will also focus the possibility to access the temperature and momentum dependence of the interaction thanks to development in the phenomenological models and the new and upcoming experimental data.
Furthermore, recent data on heavy baryon production ($\Lambda_c$, $\Xi_c$, $\Omega_c$) have shown unexpected large baryontomeson ratio and are allowing to acquire new information about the hadronization process in the heavy quark sector going from $e^+e^$, ep, pp, pA and AA collisions challenging the universality of the fragmentation function and making evident the role of the medium in the hadronization process.
The dominant interaction between a heavy quark and antiquark at low energy is described through the static potential. The real part of the potential becomes screened with a screening mass proportional to the temperature, and the imaginary part of the potential gives boundstates a nonzero width. As the temperature increases boundstates can disappear either because they are no longer supported by the screened potential, or because they become wide resonances. We calculate nexttoleading order corrections to the static potential using finite temperature perturbation theory and study their effect on the dissociation temperature of heavy quarkonia. We also study the effect of anisotropy on boundstate energies.
Fragmentation functions, one of the key components of the factorisation theorem used for computing cross sections for heavyflavour hadron production, are typically constrained in $\textrm e^{+}\textrm e^{}$ and ep collisions due to their nonperturbative nature.
However, recent measurements of charmhadron spectra and ratios at the LHC have questioned the universality of fragmentation functions across leptonic and hadronic collision systems.
This contribution presents measurements of heavyflavour tagged jets and correlation measurements involving heavyflavour hadrons. These measurements provide complementary, and more differential, insights on heavyquark production, fragmentation and hadronisation with respect to singleparticle observables.
The studies presented include measurements of the longitudinal jet momentum fraction carried by D$^{0}$ mesons and $\rm{\Lambda^{+}_{c}}$ baryons reconstructed inside jets in pp collisions. Additionally, the observation of the deadcone effect, influencing the heavyquark parton shower and performed via the measurement of D$^{0}$tagged jets in pp collisions, will be discussed.
We will also present the measurements of azimuthal correlations between D mesons and charged particles in both pp and pPb collisions, to provide a quantitative access to the angular profile, transversemomentum and multiplicity distributions of the jets produced by the heavyquark fragmentation. To gain a deeper understanding on possible difference in charmquark hadronisation into mesons or baryons, the comparison of azimuthal correlations between $\Lambda_{c}^{+}$ baryons and D mesons with charged particles in pp collisions will be also discussed.
Charm quarks, due to their significant mass, serve as an excellent tool for investigating the deconfined medium composed of quarks and gluons. These charm quarks interact with this medium and carry crucial information about it before they undergo hadronization to form heavy flavor hadrons. In this study, we employ the color string percolation model (CSPM) and the van der Waals Hadron Resonance Gas (VDWHRG) model to study the diffusion of charm quarks and the $D^{0}$ meson in both the deconfined and hadronic phases, respectively. CSPM, a QCDinspired model, proposes that the colored strings are stretched between the partons of the colliding nuclei. As a wellestablished theoretical framework, it has been employed to compute a range of thermodynamic and transport properties of the matter formed in ultrarelativistic hadronic and heavyion collisions. Conversely, the VDWHRG model is a modified hadron resonance gas model. It considers both attractive and repulsive interactions among the hadrons. This model is successful in explaining various lattice QCD results up to a temperature of $180~\rm{MeV}$. We estimate the drag coefficient $(\gamma)$ and diffusion coefficients in both momentum $(B_{0})$ and coordinate space $(D_{s})$ using the formalism of the CSPM model for the deconfined phase and the VDWHRG model for the hadronic phase. Our findings indicate the existence of a minima for the spatial diffusion coefficient near the deconfinement temperature. This minima suggests a phase transition.
Furthermore, we delve into the phenomenon of melting of charmed hadrons. This is achieved by computing the charm susceptibilities using the VDWHRG model. Our findings indicate a smooth transition in the vicinity of the deconfinement region at a vanishing chemical potential, suggesting a crossover transition. The net charm fluctuations can be deduced experimentally by considering the net number fluctuation of the $D^{\pm}$ meson. This has not been executed in experiments thus far. Nevertheless, with ALICE Run3 progressing towards increased luminosity and improved detection capabilities, this study can be conducted experimentally. This study provides pivotal insights into the characteristics of charm quarks and open charm hadrons, thereby broadening the understanding of the interaction of heavy flavors within a thermalized medium.
Microscopic approach based on quantum chromodymanics (QCD) is the most challenging ab initio theory for nuclear structure physics. In this respect, QCD sum rule gives a powerful tool, but numerically not highly demanding, to cross a bridge the QCD and hadron spectroscopy such as meson and baryon masses in terms of chiral symmetry breaking due to quark condensation. In nuclear medium, a partial restoration of the chiral symmetry breaking is found in the pionic atom experiments.
In my talk, I will present the QCD sum rule approach to the anomaly in the mass difference of mirror nuclei, known as OkamotoNolenSchiffer (ONS) anomaly, which is not yet solved by fully microscopic theory. Our approach is intimately related with the partial restoration of the chiral symmetry breaking in nuclear medium and provides a quantitative solution of the ONS anomaly in the mass difference between protons and neutrons in nuclear medium. I will also mention the charge symmetry breaking effect in hyper nuclei which is observed recently.
QCD sum rule approach is a powerful tool to implement QCD dynamics into hadron and nuclear manybody physics even for finite density.
We applied the QCD sum rule approach to derive a nuclear charge symmetry breaking (CSB) energy density functional (EDF), which describes the OkamotoNolenShiffer anomaly successfully.
As the next step, we propose an approach to derive the charge independence breaking (CIB) EDF from the low energy constants of the chiral Lagrangian.
We also apply the derived CSB and CIB EDFs to nuclear structure calculation.
The formal concept of isospin has been introduced to explain the apparent exchange symmetry between neutrons and protons [1]. However, if the nuclear force were the same for protons and neutrons properties such as masses and excitation energies would depend only on the mass number A. Hence, in the absence of isospinnonconserving effects, two isobaric analog states would be completely degenerate. Naturally, this is never the case since the Coulomb force will lift this degeneracy, but a large degree of symmetry is expected to remain in the underlying wave functions.
In recent years, many theoretical [2–4] and experimental [5–21] efforts have been devoted to study the origin of these isospin asymmetries. Isospinsymmetrybreaking probes include Triplet Energy Differences (TED) [5–11] and Mirror Energy Differences (MED) [12–20], where differences in excitation energies between isobaric analog states are analysed in all three T$_z$ = −1, 0, 1 members of a T = 1 triplet for the former, and in mirror pairs for the latter. These studies have shown that electromagnetic effects within the shell model alone cannot explain these energy differences, suggesting other effective isospinnonconserving (INC) interactions are missing from current models.
In this talk, the outcome of recent experiments intended to improve our understanding of isospinsymmetry breaking effects will also be presented, including the first observation of γrays between states in $^{94}$Ag.
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The significance of finite temperature effects in nuclear dipole transitions is evident across various applications in nuclear physics and astrophysics [14]. To describe temperature effects in electromagnetic transitions, we developed a selfconsistent finite temperature relativistic quasiparticle random phase approximation (FTRQRPA) based on relativistic energy density functional with point coupling interaction [5,6]. The isotopic chains of 4060Ca and 100140Sn closed and openshell nuclei are considered to study the evolution of electric dipole (E1) and magnetic dipole (M1) transitions at temperatures ranging from T=0 to 2 MeV. The analysis reveals that E1 giant resonance is moderately modified with temperature increase, and new lowenergy excitations appear at higher temperatures, making a pronounced impact, particularly in neutronrich nuclei. This happens because of the unblocking of new transitions above the Fermi level due to thermal effects on singleparticle states. Similarly, for the case of M1 excitations, an interesting result is obtained for 40,60Ca nuclei at higher temperatures, i.e., the appearance of M1 excitations, which are forbidden at zero temperature due to fully occupied (or fully vacant) spinorbit partner states. Additionally, the M1 strength peaks undergo a notable shift towards lower energies in Ca and Sn nuclei, primarily attributed to the decrease of spinorbit splitting energies and the weakening of the residual interaction. This effect is particularly pronounced, especially above critical temperatures (Tc), where the pairing correlations vanish. In conclusion, the E1 and M1 responses demonstrate considerable dependence on temperature, and their effects could be important in modeling gamma strength functions and their applications in astrophysically relevant nuclear reaction studies.
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In this talk, an ab initio study of infinite nuclear matter is presented within a recently introduced Green's function approach based on the stateoftheart algebraic diagrammatic construction (ADC) scheme [13].
The goal is, on the one hand, to show the power of the method, that allows to access not only the equation of state (EOS), but also singleparticle properties such as the momentum distributions and the onenucleon spectral functions.
On the other hand, new predictions for the popular chiral interactions NNLO_{sat} and Delta NNLO Go are presented and validated by a comparison with coupledcluster calculations [4], and the saturation properties are shown to be different from what thought previously.
Finally, as an example of the interest of nuclear matter, its connections to and impact on the nuclear energy density functional (EDF) are outlined [1,5].
[1] F. Marino, PhD thesis, University of Milano (2023)
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[3] F. Marino, C. Barbieri and G. Colo', in preparation
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Ever wondered about why the 27 kilometer Large Hadron Collider was built and what scientists do with it? Then this is the talk for you! The large hadronic collider is the Swiss army knife of experiments, and investigates anything from new particles and forces to the birth of the universe. As one of the physicists who works with the enormous detectors that record the collisions of the Large Hadron Collider, I will not only convince you that particle physics is necessary and interesting for everyone, but also on the fun and social aspects of this exceptional human effort to understand the building blocks of matter.
Quantum Chromodynamics (QCD) predicts a deconfined state of quarks and gluons: Quark Gluon Plasma (QGP). Studying the transport and medium properties of QGP greatly deepens our understanding of the strong interaction. Heavy quarks created from the hard scatterings in heavyion collisions are golden probes of the medium, by providing insights into inmedium energy loss, diffusion behaviors and hadronization mechanisms in the unique kinematic phase space. It is a great time to look back on what have been learned from heavy flavour, and embrace the new data and new experiments at LHC and RHIC.
In this talk, I will discuss the recent fruitful experimental studies of open heavy flavour in heavyion collisions and the perspectives for the future experiments.
Driven by the need to have a QCDbased determination of the hadron spectrum, nuclear structure, and electroweak decays, the lattice QCD community has been making impressive progress towards studying two and threehadron scattering amplitudes. Being defined in a finiteEuclidean spacetime, the notion of scattering is absent within lattice QCD, and conceptually such studies are naively impossible. In this talk, I review formal obstacles that have been overcome, as well as the very first threeparticle scattering amplitudes that have been constrained via lattice QCD.
The femtoscopic technique has emerged as a power tool to extract the strong interactions between pairs of unstable hadrons. In this talk, we show how one can apply such a technique to decipher the nature of recently discovered exotic hadrons. We show how the correlation functions are inherently connected with the underlying strong interactions in the presence of a virtual, bound, or resonant state. As examples, we show how it can determine the spins of the pentaquark states Pc(4440) and Pc(4457) and whether Zc(3900)/Zcs(3985) is a resonance or virtual state.
Recent advancements have facilitated the approximate computation of lightcone correlation functions in lattice QCD through the evaluation of their Euclidean counterparts. In this presentation, we will provide a brief overview of these significant developments that have direct implications for Generalized Parton Distributions.
The recently discovered abundance of exotic hadrons is rapidly expanding our understanding of the bound states allowed by QCD. However, basic questions about the structure of these new particles remain unanswered. Measurements of these exotic hadrons and their interactions with the QCD medium provides a new avenue to investigate their properties. Additionally, the production of hadrons with more than three quarks presents new testing grounds for models of particle transport and recombination in hadron collisions. This talk will explore new data on exotic hadrons, various models of the properties, and discuss recent and future measurements in heavy ion collisions.
The ePIC experiment at the ElectronIon Collider (EIC) includes a dualradiator RICH (dRICH) detector for PID in the forward region. This is to provide hadron particle identification capability to the experiment for the indepth investigation of the nucleon structure planned at the EIC, enabling in particular the study of SemiInclusive DIS (SIDIS) events. SIDIS events probe the confined motion of quarks and gluons inside the colliding hadron, which are encoded in the transverse momentum dependent parton distribution functions (TMD PDFs,).
The dRICH will be equipped with 3x3 mm$^2$ silicon photomultipliers (SiPM) for Cherenkov light detection over a surface of $\approx$ 3 m$^2$ ($\approx$ 300k readout channels). This will be the first HEP application of SiPMs for a RICH detector. Despite the advantages (mainly cost and immunity from magnetic field), the SiPMs are not radiation hard and show a rapid increase of the dark count rate (DCR) due to the radiation load. The EIC environment will be moderately hostile: at the dRICH location a fluence of ~ 2$\cdot$ 10$^7$ 1MeV n$_{eq}$ / cm$^2$ is expected every fb$^{1}$ of integrated luminosity delivered by the accelerator, with the total NIEL dose therefore not exceeding 10$^{11}$ 1MeV n$_{eq}$/cm$^2$.
A robust R&D program was started since some years to demonstrate it will be possible to preserve singlephoton counting capabilities in such environment and maintain the DCR below ∼ 100 kHz/mm$^2$, with an emphasis on the recovery of the radiation damage via hightemperature annealing cycles. SiPM irradiation campaigns have been performed with protons and neutrons using SiPM from different manufacturers and with different characteristics (in particular the SPAD size). The annealing cycles were performed using different techniques, via heating in oven and electrically induced thermal annealing flowing high current in the sensors (Joule annealing). A comprehensive set of results comparing sensor performance following repeated annealing cycles will be presented, together with the solutions being identified finalising the detector design.
Further DCR control and background reduction can be achieved with operation at low temperature and precise timing selection, thanks to the SiPM intrinsic resolution and the use of a new frontend ASIC (ALCOR), with appropriate time resolution. Beam test results obtained at CERN PS with a large area (1280 3x3 mm$^2$ SiPM sensors) prototype will be also reported, where advanced compact prototypes of the dRICH integrated (sensors, frontend electronics, cooling) Photo Detector Unit have been successfully tested.
A fixedtarget experiment at LHC to measure directly the dipole moments of charm baryons is presented. The experimental approach is based on the phenomenon of spin precession for channeled particles in bent crystals and on the precise measurement of the charm baryon polarisation. The measurement of the magnetic moment of charm baryons would allow to determine the charm quark magnetic moment. A proofofprinciple test at LHC is foreseen during LHC Run3 to prove the feasibility of the experiment. The latest progress, the advancements and the perspective for the future experiment will be discussed.
Electromagnetic form factors, which are accessible via elastic electron scattering, encapsulate information on the charge and current structure inside the nucleons. The data on the nucleon form factors allows flavour separation analysis, for which early measurements have provided striking results indicating to a diquark component in a nucleon. Form factors also provide important constraints on Generalized Parton Distributions.
The large acceptance Super Bigbite Spectrometer (SBS) developed in Jefferson Lab Hall A seeks to extend measurements of the nucleon form factors to unprecedented high values of the four momentum transfer squared Q2. The 11 GeV electron beam at Jefferson Lab makes this possible. The electric form factor (GEn ) of the neutron is the least well understood of the four Sachs form factors, due to its small magnitude and the experimental complexity required in accessing it. The GENII experiment, which uses novel convection type polarised helium3 targets, will provide results for $G^E_n$ at three kinematic points 2.9, 5.5 and 9.9 GeV2. I provide an overview of the experimental technique and present preliminary results from the completed kinematic points.
The progress towards the direct measurement of electric and magnetic dipole moments of Lambda baryons at LHCb is presented. In addition, the measurement of magnetic dipole moments for particles and antiparticles would allow a test of the CPT symmetry. The experimental technique is based on the spin precession of Lambda baryons in the dipole magnet of the LHCb tracking system. Lambda baryons decaying downstream of the magnet have been reconstructed exploiting the excellent capabilities of the LHCb detector and developing adhoc techniques. The performance in the reconstruction of Lambda baryons from Lb>J/Psi Lambda decays using Run1Run2 data are discussed, along with the perspectives for the future dipole moment measurements in Run3.
Using the world’s largest samples of J/psi and psi(3686) events produced in e+e annihilation, BESIII is uniquely positioned to study light hadrons in radiative and hadronic charmonium decays. In particular, exotic hadron candidates including multiquark states, hybrid mesons and glueballs can be studied in high detail. Recent highlights on the light exotics searches, including observation of an isoscalar spinexotic 1+ state η1(1855) in J/ψ→γηη′, observation of X(2600) in J/ψ→γπ+πη′, observation of the anomalous shape of X(1840) J/ψ→γ3(π+π), in will be presented.
A precise description of pionpion interactions at low energies is fundamental for many processes in hadronic physics. We present preliminary work, which introduces several improvements with respect to a previous dispersive analysis*. This includes a refined treatment of inelasticities, the introduction of Gwaves, the study of Forward Dispersion Relations (FDRs) up to 1.6 GeV, and data description up to 1.8 GeV. From the FDR output, we extract resonance poles by means of continued fractions.
*In progress J.R. Peláez, P. Rabán and J. Ruiz de Elvira
**J.R. Pelaez, A. Rodas, and J. Ruiz De Elvira. Global parameterization of pipi scattering up to 2 GeV. Eur.Phys.J.C, 79(12):1008, 2019.
Presented here is a theoretical model designed to investigate double pion photoproduction, within the photon energy range of 3.0 to 3.8 GeV and momentum transfer range of $0.4<t<1.0$ GeV$^2$. This model integrates contributions from resonances such as the $\rho(770)$, as well as the primary background from the Deck mechanism.
Utilizing the Regge formalism and incorporating the established Deck mechanism, the model emphasizes the significance of the $\rho(770)$ resonance, highlighting its role in representing $P$wave contributions arising from pomeron alongside other exchanges. However, at high momentum transfers, indications of schannel helicity nonconservation emerge, suggesting the involvement of additional partial waves, notably the $S$ and $D$ waves. The model is further extended to include scalar mesons such as $f_0(500)$, $f_0(980)$, and $f_0(1370)$, along with the tensor meson $f_2(1270)$, influencing $S$ and $D$wave effects, respectively. Predictions of angular moments are compared with CLAS data, and the analysis further explores the $t$dependence of the Regge amplitude residue function for subdominant exchanges.
One of the earliest predictions of Quantum Chromodynamics (QCD) is the existence of color singlet puregauge states known as glueballs. However, despite this anticipation, consensus on their theoretical properties and experimental evidence remains elusive. Twogluon glueball states have been quite abundantly explored both theoretically and experimentally. One may cite, for example, on the theory side, results from various phenomenological approaches, from functional methods, and lattice QCD. Notable experimental endeavors, such as PANDA, Crystal Barrel or WA102, continue to seek evidence for the states. In contrast, threegluon glueballs garnered less attention, due to the technical complexity of the task. On the theory side, the lattice QCD spectrum being insensitive to the number of gluons, it should encompass threegluon levels, while, on the experimental side, the possible observation of an odderon exchange at TOTEM is still debated.
This presentation aims to apply the helicity formalism to the description of two and threegluon systems within constituent models. After revisiting onebody helicity states, the twobody formalism is presented and applied to describe twogluon glueballs. The incorporation of symmetries and parity reveals selection rules consistent with lattice QCD results. Introducing dynamical considerations yields a quantitative spectrum of twogluon glueballs that can also be compared to lattice results. These results are also compared to some obtained by considering that gluons have spin degreesoffreedom, concluding that helicity is a significant ingredient in reproducing the spectrum.
In a subsequent phase, the threebody helicity formalism is employed to model threegluon glueball states. Expected symmetries and parity are implemented using Berman's definition for threebody helicity states and the obtained selection rules are compared with existing literature results. Before concluding, perspectives on acquiring a quantitative spectrum for threegluon glueballs are presented.
The nontrivial quark structure of light scalar mesons f0(500), f0(980) and a0(980) remains controversial for many years. In passed years, BESIII studied them via several semileptonic D decays (D0>a0(980) e+nu, D+ > a0(980)0 e+nu, Ds+ > a0(980)0 e+nu, D+ > f0(500)/f0(980)e+nu, D+ > f0(500)mu+nu, Ds+ > f0(500)/f0(980)e+nu). Especially, the measurement of D > f0/a0 form factor could shed light on the nature of them. In this talk, I will review all studies about light scalar mesons via semileptonic D decays at BESIII. A short outlook would be given based on BESIII new data in the future.
The system of η and η′ offers a flavorconserving laboratory to test the lowenergy QCD and to search for new physics Beyond the Standard Model. The symmetry properties of QCD at lowenergy, such as the chiral symmetry or the axial anomalies, are manifested in the decays of η and η′. Thus, a study of $\eta^{(\prime)}$ will yield light on our understanding of the origin and the dynamics of QCD confinement. In addition, the $\eta^{(\prime)}$ meson has quantum numbers of vacuum (except parity) with its strong and electromagnetic decays being either anomalous or forbidden to the lowest order due to symmetries or angular momentum conservation. This enhances the relative importance of higher order contributions, making the rare $\eta^{(\prime)}$ decays a sensitive hadronic probe for weaklycoupled new forces. Searching for subGeV dark gauge boson candidates, and the Cviolating, Pconserving interactions in various $\eta^{(\prime)}$ decays will extend our knowledge of the dark sector and explore new sources of CP violation that is needed to explain the observed matter and antimatter asymmetry in the universe. The status and the new experimental opportunities for the $\eta^{(\prime)}$ physics will be presented.
The electromagnetic form factor of the charged pion encodes relevant information in hadron dynamics. On the one hand, its phase is related (modulo isospinbreaking corrections) to the universal $\pi\pi$ $P$wave phase shift, that appears in a variety of hadronic processes. On the other hand, it appears as an essential input to describe hadronic electromagnetic interactions when employing dispersive formalisms. Furthermore, it is relevant to extract information about vector meson resonances. In this work, we employ a dispersion relation for the modulus of the form factor that allows to reconstruct its phase from its modulus above the unitarity cut. The latter has been extensively measured to high precision at $e^+e^$ colliders in the region ranging from threshold up to 3 GeV.
The formalism allows a databased approach to extract the phase from hreshold up to 2.5 GeV, well beyond the inelastic threshold where standard dispersive approaches cannot be applied. In addition, we provide relevant results, including the charged radius, the spacelike behavior, the extraction of the $P$wave $\pi\pi$ phase shift, or the less known (isospinbreaking) isoscalar form factor.
Reference: https://arxiv.org/abs/2403.07121
The sensitivity of the rare decays $\eta\to\pi^{0}\gamma\gamma$ and
$\phi\to\pi^{0}\eta\gamma$ to signatures of a leptophobic $B$ boson in the MeVGeV mass range is analyzed in this talk.
By adding an explicit $B$boson resonance exchange to the Standard Model contributions from vector and scalar meson exchanges,
and employing experimental data for the associated branching ratios
and invariant mass spectra,
it allows us to improve the current constraints on the $B$boson mass $m_{B}$ and coupling to Standard Model particles $\alpha_{B}$.
This abstract presents a thorough analysis of the φ → 3π decay amplitude, including a study of its behavior using different phase shift parametrizations. Based on recent experimental results, we delve into the intricacies of this decay process and also explore the φπ0 transition form factor. By employing the Khuri–Treiman equations approach, we establish a strong agreement between the Dalitzplot parameters linked to the φ → 3π decay. These parameters, obtained from an amplitude that has undergone a specific subtraction, align closely with the latest findings from the KLOE experiment. Moreover, our investigation unveils insights into the transition form factor for φπ0, especially in the context of lower and moderate energy levels. Our analysis of the φ(1020) → 3π amplitude enables us to deduce this form factor, which notably matches experimental data from KLOE and BaBar experiments. This remarkable consistency highlights the excellent fit between our developed theoretical framework and the observed behaviors of the φ(1020) meson dynamics.
The $D^{+} \to K_s^0 \pi^{+} \eta$ reaction was recently measured by the BESIII collaboration [1]. The reaction is actually $D^{+} \to \bar{K}^0 \pi^{+} \eta$, with the $\bar{K}^0$ observed as a $K_s^0$ state.
We study the $D^{+} \to \bar{K}^0 \pi^{+} \eta$ reaction, where the $a_0(980)$ excitation plays a dominant role. We consider mechanisms of external and internal emission at the quark level, hadronize the $q \bar{q}$ components into two mesons, and allow these mesons to undergo finalstate interaction, where the $a_0(980)$ state is dynamically generated. While the production of $a_0(980)$ is the dominant term, we also find other terms in the reaction that interfere with this production mode. Through interference with it, they lead to a shape of the $a_0(980)$ significantly different from the one observed in other experiments, with an apparently much larger width. I will give a presentation based on Ref. [2] and also discuss the $D^0 \to K^{} \pi^{+} \eta$ reaction by changing a $\bar{d} \to \bar{u}$ quark in Ref. [3].
[1] M.~Ablikim et al. [BESIII], arXiv:2309.05760 [hepex].
[2] N. Ikeno, J. M. Dias, W. H. Liang and E. Oset, arXiv:2402.04073 [hepph].
[3] G. Toledo, N. Ikeno and E. Oset, Eur. Phys. J. C81, 268 (2021).
The proposed ElectronIon Collider (EIC) will utilize highluminosity highenergy electron+proton ($e+p$) and electron+nucleus ($e+A$) collisions to solve several fundamental questions, which include searching for gluon saturation and studying the proton/nuclear structure. Due to their high masses ($M_{c,b} > \Lambda_{QCD}$), heavy quarks do not transfer into other quarks or gluons once they are produced. This feature makes the heavy flavor product an ideal probe to explore how a heavy flavor hadron is formed from a heavy flavor quark, which is referred to as the heavy quark hadronization. A series of heavy flavor hadron and jet simulation studies, which include the projected EIC detector performance, have been carried out recently. We will present the heavy flavor hadron and jet reconstruction capability, the projected nuclear modifications of heavy flavor hadrons inside jets, and heavy flavor jet substructure distributions in $e+p$ and $e+A$ collisions with the EIC project detector design and the projected integrated luminosities at the EIC. These proposed EIC heavy flavor measurements will provide a unique path to explore the flavor dependent fragmentation functions and reveal the heavy quark nuclear transport properties in cold nuclear medium. The expected results will provide great discriminating power in separating different theoretical calculations and help constraining initial and final state effects for heavy ion measurements at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC).
We present results for dipion transitions between heavy quarkonium states of large principal quantum number for which the multipole expansion does not hold. We combine the QCD effective string theory with the Chiral Lagrangian in order to get the appropriate vertexes.
We extend the results to transitions for which the initial estate is a heavy quarkonium hybrid. We observe that the dipion spectrum is qualitatively different if the initial state is a hybrid or a quarkonium.
This presentation will discuss recent experimental discoveries in the realm of charmonium decays, containing four independent measurements at BESIII. 1) The observation of the ψ(3686) → 3ϕ decay. This observation sheds light on the rare decay process of the ψ(3686) resonance into three φ mesons, providing valuable insights into the dynamics of charmonium decays. No significant structure is observed in the ϕϕ invariant mass. 2) The search for ηc(2S) → π+π−ηc and ηc(2S) → π+π−K0SK±π∓ decays. This study aims to explore the decay properties of the ηc(2S) meson, offering new perspectives on its decay modes and contributing to our understanding of charmonium states. 3) The observation of the ψ(3686) → Ω−K+ antiΞ0 + c.c. decay. This process is observed for the first time. Possible baryon excited states are searched for in this decay, but no evident intermediate state is observed with the current sample size. 4) The observation of χcJ → 3(K+K−). All the decays from χc0, χc1, and χc2 are observed for the first time.
The last decade has seen a wealth of discoveries of new hadronic states with heavy quarks, many of which are outside the scope of the naive quark model of conventional mesons and baryons. The LHCb experiment, designed to research heavy flavor hadrons in $pp$ collisions, is especially well suited to investigate the nature of these states. An underexploited source of hadronic resonances are semileptonic $B$decays, which offer an environment in which these states can be studied without the complication of crossed channel effects. This presentation will summarize recent developments in tetraquark studies at LHCb as well as present an outlook for tetraquark spectroscopy in semileptonic $B$decays with an emphasis on their possible molecular nature.
We study the potential of X(3872) at finite temperature in the BornOppenheimer approximation under the assumption that it is a tetraquark. We argue that, at large number of colors, it is a good approximation to assume that the potential consists in a real part plus a constant imaginary term. The real part is then computed adapting an approach by Rothkopf and Lafferty and using as input lattice QCD determinations of the potential for hybrids. This model allows us to qualitatively estimate at which temperature range the formation of a heavy tetraquark is possible, and to propose a qualitative picture for the dissociation of the state in a medium. Our approach can be applied to other suggested internal structures for the X(3872) and to other exotic states.
Authors: S. Glässel, V. Kireyeu, G. Coci, V. Voronyuk, M. Winn, J. Aichelin, C. Blume, and E. Bratkovskaya
We investigate the influence of the equationofstate (EoS) of strongly interacting hadronic and partonic matter created in heavyion collisions on the light cluster and hypernuclei production within the PartonHadronQuantumMolecular Dynamics (PHQMD) microscopic transport approach (PHQMD) [15]. The PHQMD is a microscopic nbody transport model based on the QMD propagation of the baryonic degrees of freedom, where the clusters are formed dynamically, via {\bf 'potential' mechanism}, i.e. by potential interactions between nucleons and hyperons, and recognized by by the Minimum Spanning Tree (MST) algorithm which is identifying bound clusters by correlations of baryons in coordinate space.
Additionally, {\bf 'kinetic' mechanisms for deuteron production} is incorporated by catalytic hadronic reactions accounting all isospin channels of the various $\pi NN\leftrightarrow \pi d$, $NNN\leftrightarrow N d$ reactions which enhances deuteron production as well as considering the quantum nature of the deuteron by mean of its finite size modelled by the finitesize excluded volume effect in coordinate space and projection of relative momentum of the interacting pair of nucleons on the deuteron wavefunction in momentum space, leads to a strong reduction of d production, especially at target/projectile rapidities [4].
Whereas in the previous PHQMD calculations we employed a static interaction between nucleons, now we include a {\bf momentum dependence interaction}. The parameters of the momentum dependent potential are fitted to the 'optical' potential, extracted from elastic pA scattering data. The potential is increasingly repulsive up to $E_{kin}\sim 1.5$ GeV, therefore its influence depends on the beam energy. A momentum dependent interaction acts very differently on flow observables like $v_1$ or $v_2$ and cluster rapdity distributions and brings the calculations even closer to the experimental data as a comparison with STAR data shows.
We have furthermore implemented {\bf the coalescence approach in the PHQMD } what allows to compare directly and for the same underlying dynamics the cluster yields, created by MST+kinetic mechanisms and coalescence mechanism. We could establish that both methods yield different cluster rapidity distributions. This allows to {\bf determine the cluster production mechanism experimentally}. Finally we will present a solution of the 'ice in the fire' puzzle, the question how cluster can survive the expansion of the hot and strongly interacting fireball at midrapidity.
[1] J. Aichelin, E. Bratkovskaya, A. Le Fevre, V. Kireyeu, V. Kolesnikov, Y. Leifels, V. Voronyuk and G. Coci, Phys. Rev. C101 (2020) 044905, [arXiv:1907.03860 [nuclth]].
[2] S. Glässel, V. Kireyeu, V. Voronyuk, J. Aichelin, C. Blume, E. Bratkovskaya, G. Coci, V. Kolesnikov and M. Winn, Phys. Rev. C105 (2022) 014908, [arXiv:2106.14839 [nuclth]].
[3] V. Kireyeu, J. Steinheimer, J. Aichelin, M. Bleicher and E. Bratkovskaya, Phys. Rev. C105 (2022) 044909, [arXiv:2201.13374 [nuclth]].
[4] G. Coci, S. Glässel, V. Kireyeu, J. Aichelin, C. Blume, E. Bratkovskaya, V. Kolesnikov and V. Voronyuk, Phys. Rev. C108 (2023) 014902, [arXiv:2303.02279 [nuclth]].
[5] V. Kireyeu, G. Coci, S. Glaessel, J. Aichelin, C. Blume and E. Bratkovskaya, [arXiv:2304.12019 [nuclth]].
NA61/SHINE is a multipurpose fixedtarget experiment located at CERN SPS. One of its main goals is to study the phase diagram of strongly interacting matter. For this purpose, a unique twodimensional scan in beam momentum 13A150(8)A GeV/c and the system size including p+p, p+Pb, Be+Be, Ar+Sc, Xe+La, and Pb+Pb collisions was performed. The main goal of the strong interaction program is to understand the onset of deconfinement and locate the critical point of strongly interacting matter.
The latest results from the NA61/SHINE strong interaction program will be reviewed, focusing on hadron spectra and fluctuations in various collisions. The new results on strangeness production, particularly the ratio of positively charged kaons to pions, will be presented,including the first results for Xe+La collisions. The presentation will also review the recent NA61/SHINE results on proton and negatively charged hadrons intermittency to search for the QCD critical point. The NA61/SHINE data will be compared with other experimental results and predictions from theoretical models like EPOS, PHSD, UrQMD, and confronted with Powerlaw model predictions.
The study of strongly interacting matter under extreme conditions is one of the most important topics in the exploration of Quantum
Chromodynamics (QCD).
In this talk, we highlight new measurements by HADES, the HighAcceptance Dielectron Spectrometer located at the SIS18 at GSI in Darmstadt, which is currently the only experimental setup with the unique ability to measure rare and penetrating probes at the high$\mu_B$ frontier of the QCD phase diagram.
We discuss recent high statistics results on collective flow phenomena in Au+Au and Ag+Ag collisions. Moreover, flow coefficients $v_{n}$ up to the $6^{\text{th}}$ order are investigated for the first time in this energy regime. Their combined information allows to construct for the first time a full 3D picture of the angular particle emission in momentum space. The multidifferential analysis in different centrality classes over a large region of phase space will be shown and various scaling properties will be discussed.
The data provide essential constraints for theoretical transport models utilised in the determination of the properties of dense baryonic matter, such as its viscosity and equationofstate (EOS).
Supported by the Helmholtz Forschungsakademie HFHF and the BMBF grant 05P21RFFC3.
Despite the f0(980) hadron having been discovered half a century ago, the question about its quark content has not been settled: it might be an ordinary quarkantiquark meson, a tetraquark exotic state, a kaonantikaon molecule, or a quarkantiquarkgluon hybrid. We report strong evidence that the f0(980) state is an ordinary quarkantiquark meson, inferred from the scaling of elliptic anisotropies (v2) with the number of constituent quarks (nq), as empirically established using conventional hadrons in relativistic heavy ion collisions. The f0(980) state is reconstructed via its dominant pipi decay channel, in protonlead collisions recorded by the CMS experiment at the LHC, and its v2 is measured as a function of transverse momentum (pT). It is found that the nq = 2 (quarkantiquark state) hypothesis is favored over nq = 4 (tetraquark or molecule states) by 7.7, 6.3, or 3.1 standard deviations in the pT < 10, 8, or 6 GeV/c ranges, respectively, and over nq = 3 (quarkantiquarkgluon hybrid state) by 3.5 standard deviations in the pT < 8 GeV/c range. This result represents the first determination of the quark content of the f0(980) state, made possible by using a novel approach, and paves the way for similar studies of other exotic hadron candidates.
Heavyion collision experiments are a valuable tool for studying nuclear properties. Accurately modeling entropy production at the initial collision time and subsequent collective evolution is crucial to connect the nuclear structure to heavyion measurements. In this talk, we argue that, based on experimental data, it is reasonable to assume scaleinvariance at the initial state, meaning the produced entropy scales similarly to the thickness function of the nuclei participants. This implies that the observables receive a small contribution from the entropy production process and more from nuclear properties in ultracentral symmetric heavyion collision. With this conclusion, we employ cluster expansion decomposition to study the ellipticity fluctuation and introduce a formula for it. The formula is common for all scaleinvariant initial state models and depends on the onebody and twobody density of the colliding nuclei. We show that this result is compatible with initial state models that obey scale invariance, such as TrENTo, with various values for p and initial state models based on CGC. We also explore its implications for studying nuclear properties in the isobar ratio measurements.
Modern experimental facilities, new theoretical techniques for the continuum boundstate problem and progress with latticeregularized QCD may have provided indications that soft quark+quark (diquark) correlations play a crucial role in hadron physics. For example, theory indicates that the appearance of such correlations is a necessary consequence of dynamical chiral symmetry breaking, viz. a corollary of emergent hadronic mass that is responsible for almost all visible mass in the universe; experiment has uncovered signals for such correlations in, for instance, the flavourseparation of the proton's electromagnetic form factors; and phenomenology suggests that diquark correlations might be critical to the formation of exotic multiquark hadrons. A broad spectrum of such information is evaluated in this talk, with a view to consolidating the facts and therefrom moving toward a coherent, unified picture of hadron structure and the role that diquark correlations might play.
The dilemma between molecular states and compact quark states is the subject of a continuous debate in hadron physics.In this talk, based on our recent two works [PLB846,138200 and PRD108,114017] we address the issue of the compositeness of hadronic states for Tcc(3875) in the single channel calculation and also an extension to X(3872) in the coupled channel calcualtion. We develop the general formalism to study the molecular probability, scattering length and effective range. The calculations are presented in several scenarios, also compare with the present experimental information, concluding the unavoidable molecular nature of these two states.
We face the inverse problem of obtaining the interaction between coupled channels from the correlation
functions of the the 𝐷0𝐾+, 𝐷+𝐾0, and 𝐷+𝑠 𝜂 channels,from where the 𝐷∗𝑠0(2317) state emerges. We use synthetic data extracted from an interaction model based on the local hidden gauge approach and find that the inverse problem can determine the existence of a bound state of the system with a precision of about 20 MeV. At the same time, we can determine the isospin nature of the bound state and its compositeness in terms of the channels. Furthermore, we evaluate the scattering length and
effective range of all three channels, as well as the couplings of the bound state found to all the components.
Lastly, the size parameter of the source function, 𝑅 can be obtained from a fit to the data with relatively high accuracy. These findings show the value of the correlation function to learn about the meson–meson interaction for systems which are difficult
to access in other present facilities.
We apply the same method to the coupled
channels K0Σ+, K+Σ0, K+Λ and ηp which generated dynamically the N*(1535) state. We find that, assuming errors of the same order
than in present measurements of correlation functions, one can determine the scattering length and effective range of all channels with a very good accuracy. Most remarkable is the fact that the method predicts the existence of a bound state of isospin 1/2 nature around the mass of the N∗(1535) with an accuracy of 6 MeV.
The contribution is based on the papers
Phys.Rev.D 109 (2024) 054002 and Phys.Lett.B 847 (2023) 138281
An experimental program has been approved at the Thomas Jefferson National Accelerator Facility to measure the (ep,e’K+)Y reactions to study the spectrum and structure of excited nucleon states. New data from CLAS12 on πN, ππN, and KY electroproduction have been obtained using electron beams with energies of 6.5 and 7.5 impinging upon a liquid hydrogen target. Scattered electrons have been detected in a polar angle range of 2.5° to 4.5° by the Forward Tagger (FT) and at angles greater than 6° in the CLAS12 Forward Detector, allowing to measure the KY electroproduction differential cross section and to probe the Q2 evolution of the nucleon resonances electrocouplings in the Q2 range from 0.05 GeV2 to 3 GeV2. The Q2 dependence of excited baryons electrocouplings allows to probe the dressed quark mass over the full range of distances where the dominant part of hadron mass emerges from QCD. By studying the Q2 evolution of electroexcitation amplitudes it will be also possible to distinguish between regular N states and possible additional hybrid baryon states in the mass range of 2.0 GeV < W < 2.5 GeV where the lightest hybrid baryons are expected to be located based on LQCD studies of the N* spectrum.
Preliminary results for KY electroproduction will be reported and prospects for future studies will be discussed.
The new generation of deeply virtual exclusive experiments planned at Jefferson Lab and the EIC, in conjunction with other laboratories worldwide, purport to measure and image the internal structure of hadronic systems. To fully capitalize on the data emerging from these experiments, our collaboration has focused on combining the analysis of the experimental information with ab initio theoretical calculations, marshaling modern data science techniques. We will present our first results from our global analysis framework applied to DVCS, TCS as well as other exclusive diffractive processes with two or more hadrons in the final state. Several computational aspects from the role of specific lattice QCD quantities that are relevant for these processes to uncertainty quantification will be discussed.
In this work, we investigate the hadron interactions using the threequark potential in a constituent quark model. Threequark potentials have only been studied for simple cases because it is difficult to calculate the threecolor interaction matrix and determine the radial dependence of potential. In the case of a multiquark system, the threequark color matrix can be calculated using the permutation matrix, but when there are antiquarks, a different method must be used. In order to calculate the threequark potential, we use the commutation and anticommutation relations of SU(3) and apply it to exotic hadron configurations.
The idea of studying nuclear physics directly from the degrees of freedom of the Standard Model, quarks and gluons, has been long sought in the physics community. During the last few decades, the numerical method called lattice QCD has been able to compute the simplest quantities, such as the hadron masses, directly from first principles. When trying to address multibaryon systems, more sophisticated algorithms and analysis techniques are required in order to obtain the energy levels. In this talk, I will present the latest results from the NPLQCD collaboration from a variational study of the $NN$ systems at $m_\pi\sim800$ MeV using a large set of interpolating operators. I will also discuss the isospin singlet, strangeness −2 sector relevant for the Hdibaryon at $m_\pi\sim800$ MeV.
In this study, we employ Bayesian statistical methods to analyze nucleonnucleon scattering data within the framework of pionless effective field theory. The Bayesian analysis facilitates the quantification of uncertainties and the incorporation of prior theoretical knowledge, thereby enhancing the interpretability and reliability of the model parameters. By applying this methodology to nucleonnucleon scattering data, we aim to provide a comprehensive understanding of nuclear forces in the lowenergy regime. The results underscore the effectiveness of Bayesian methods in nuclear physics research, particularly in the context of effective field theories, where model simplicity and computational efficiency are paramount.
In recent years, many new jet substructure observables have been studied, with particular attention given to those that can be calculated by perturbative QCD. Npoint energy correlators are currently attracting both theoretical and experimental interest. The energyenergy correlators (EEC), or twopoint correlator, which emphasize the angular structure of the energy flow within jets, allow for a comprehensive study of both the perturbative and nonperturbative aspects of jet structure. Defined as the energyweighted crosssection of particle pairs inside jets, the EECs, as a function of pair distance, show a distinct separation of the perturbative from the nonperturbative regime, revealing parton flavordependent dynamics of jet formation as well as the confinement of the partons into hadrons. Extending the EEC to the threepoint correlator (E3C) is extremely interesting, as these probe the parton shower beyond 1 $\rightarrow$ 2 splittings and encode additional information about the internal structure of jets. Moreover, taking ratios of the projected E3C with the EEC offers precision tests of the coupling strength of the strong force $\alpha_{s}$.
In this talk, I will present an experimental overview of the recent measurements on EECs from the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). The measurement will include the EEC and E3C for inclusive (gluondominated) jets in pp collisions. Additionally, heavyflavortagged (reconstructed $\rm D^{0}$) jets EEC will be discussed in comparison to inclusive jet samples. This comparison offers valuable insight into flavor dependencies, such as the Casimir factors of quarks and gluons, as well as the mass of heavy quarks, in parton fragmentation and hadronization. Moreover, I will discuss comparisons with different Monte Carlo (MC) generators and theoretical predictions. This suite of measurements will serve as a baseline for future studies in heavyion collisions, allowing for disentanglement of the dynamics of the dead cone from interactions with the quarkgluon plasma.
We present a new coherent jet energy loss model for heavyion collisions. It is implemented as a Monte Carlo perturbative finalstate parton shower followed by elastic and radiative collisions with the medium constituents. Coherency is achieved by starting with trial gluons that act as field dressing of the initial jet parton. These are formed according to a GunionBertsch seed. The QCD version of the LPM effect is attained by increasing the phase of the trial gluons through elastic scatterings with the medium. The model has been validated by successfully reproducing the BDMPSZ prediction for the energy spectrum of radiated gluons in a static medium. The realistic case for LHC energy with minimal assumptions is also produced and shown. We also show the influence of various parameters on the energy spectrum and transverse momentum distribution. The model is constructed with realistic medium description and jetmedium coupling in mind.
Shortly after the beginning of the LHC heavy ion program, the CMS Collaboration reported the observation of stronger suppressions of the excited $\Upsilon$ states compared to the lower $\Upsilon\mathrm{(1S)}$ state, first in leadlead (PbPb) and then in protonlead (pPb) collisions. Such feature, anticipated in the former as a signature of the presence of a quarkgluon plasma, was however unforeseen in the latter at LHC energies. These findings prompted extensive experimental and theoretical studies of the relative suppression of quarkonia. Ultimately, a comprehensive picture of the quarkonium production in heavy ion collisions is necessary to understand the formation and interaction of bound states in strongly interacting matter, and hence to characterize its properties.
In this contribution we present the latest CMS measurements of $\Upsilon$ mesons in heavy ion collisions. These include the observation of the $\Upsilon\mathrm{(3S)}$ meson in PbPb collisions and detailed studies of the suppression of the three lowest $\Upsilon$ states in pPb and PbPb collisions. The results are compared with various models describing the nuclear modification of quarkonium production in (deconfined) media.
Systematic studies of jet substructure offer precision tests of quantum chromodynamics (QCD) in vacuum as well as at the large particle densities and high temperatures of the quarkgluon plasma (QGP) produced in heavyion collisions. The jet invariant mass is a canonical jet substructure observable which has been broadly studied for decades, both experimentally and theoretically, to qualify the shape of jets and to identify boosted particles. A proxy for the virtuality $Q$ of the initiating parton, the jet invariant mass is a perturbatively calculable probe of an uncontrolled variable in scattering experiments, though it is also dominated by nonperturbative corrections at small values, presenting an excellent test of QCD dynamics across a broad range of $Q^2$. The jet invariant mass can be combined with jet grooming procedures such as soft drop to remove soft, wideangle radiation, both enhancing the predictive strength of perturbative calculations and reducing experimental systematic uncertainties. Firstprinciples calculations are essential to estimate QCD backgrounds in particle searches in combination with Monte Carlo generators, which have surprisingly produced jet mass distributions in tension with one another. The jet invariant mass has also presented mysteries in heavyion collisions, where observed quenching modifications are in apparent disagreement with those observed for theoretically related jet angularities.
This talk presents an overview of recent jet invariant mass measurements from the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) in both pp and heavyion collisions. These measurements provide tests of QCD in vacuum and of jet quenching models, providing new critical information on nonperturbative dependence and QCD medium evolution. Comparing measurements from RHIC and the LHC provides insight on QGP dynamics at different energy scales. This talk furthermore looks forward to future precision measurements of the heavyflavor tagged jet invariant mass, which will offer a unique frontier to disentangle the QCD dead cone from Casimir color effects, while also testing novel flavor tagging algorithms and perturbative QCD with a nonzero quark mass.
Due to the spinorbit coupling, Dirac fermions, submerged in a thermal bath with finite macroscopic vorticity, exhibit a spin polarisation along the direction parallel to the vorticity vector Ω. Due to the symmetries of the Lagrangian for free massless Dirac particles, there are three independent and classically conserved currents corresponding to the vector, axial, and helical charges. We consider the mode structure of the corresponding hydrodynamical theory and derive collective excitations associated with coherent fluctuations of all three charges, recovering the known Chiral Vortical Wave as a particular case. We discuss phenomenological implications for the QuarkGluon plasma.
The study of singleparticle structure in light neutronrich systems has led to discoveries of dramatic changes which are otherwise gradual near stability, leading to the weakening and appearance of shell closures. For example, the disappearance of N = 20 and emergence of N = 16 [1, 2] as well the emergence of N = 32, 34 in calcium isotopes [3]. Pronounced trends have also been observed in stable heavier nuclei, in the changes in highj states as highj orbitals are filling. Studies of chains of stable, closedshell isotopes [4] and isotones [5] have pointed to robust mechanisms for these changes, such as the importance of a tensor interaction [6].
The ISOLDE Solenoidal Spectrometer (ISS) allows studies of the singleparticle properties of nuclear away from stability via measurements of singlenucleon transfer reactions, using the broad range of beams available at ISOLDE. ISS has been used to study singleparticle properties of nuclei, and how they are evolving, in various regions of the nuclear chart duting it’s first physics qcampaigns.
In light neutronrich nuclei the monopole shifts of singleparticle energies with changing proton occupancies have been investigated outside N=16 with a study of states populated in $^{28}$Na, mapping out the relative behaviour of the intruder states above N=20 related to the evolution of structure here. A measurement has also been made of the fragmentation of singleparticle strength in $^{31}$Mg, inside the N=20 island of inversion, where a change in groundstate structures related to the weakening N=20 shell closure occurs. Both these data can be compared to that measured previously in $^{30}$Al and $^{29}$Mg [7] to understand the systematics along N=17 and across the border of the island of inversion.
The beams available at ISOLDE allow an extension of studies of highj orbitals to N=126, with a focus on nuclei above $^{208}$Pb, where monopole shifts arise due to the filling of the proton h$_{9/2}$ orbital. The evolution of singleneutron properties outside N=126 have been investigated, with a measurement of the $^{212}$Rn(d,p) reaction, similar in scope on previous measurements south of $^{208}$Pb in $^{207}$Hg [8].
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[2] C. R. Hoffman et al., Phys. Lett. B 672, 17 (2009).
[3] D. Steppenbeck et al., Nature 502, 207 (2013).
[4] J. P. Schiffer et al., Phys. Rev. Lett. 92, 162501 (2004).
[5] B. P. Kay et al., Phys. Lett. B 658, 216 (2008), D. K. Sharp et al., Phys. Rev. C 87, 014312 (2013).
[6] T. Otsuka et al., Phys. Rev. Lett. 95, 232502 (2005).
[7] P. T. MacGregor et al., Phys. Rev. C 104, L051301 (2021).
[8] T. L. Tang et al., Phys. Rev. Lett. 124, 062502 (2020).
This material is based upon work supported by the UK Science and Technology Facilities Council [Grants No. ST/P004598/1, No. ST/N002563/1, No. ST/M00161X/1 (Liverpool); No. ST/P004423/1 (Manchester); No. ST/P005314/1 (Surrey); the ISOLSRS Grant (Daresbury)], and the European Union's Horizon 2020 Framework research and innovation program under grant agreement no. 654002 (ENSAR2) and the Marie SkłodowskaCurie grant agreement No. 665779 and the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Contract Number DEAC0206CH11357 (ANL) and the Research Foundation Flanders
Nuclear matter at subsaturation densities is expected to be inhomogeneous, owing to the existence of manybody correlations, which constitutes an essential feature for the construction of a reliable equation of state. A first emergent phenomenon related to this aspect is the fragmentation process, experimentally observed in heavyion collisions at intermediate energies as the result of mechanical (spinodal) instabilities driven by the meanfield, in connection to the occurrence of a liquidgas phase transition. On the other hand, at even smaller densities, owing to residual fewbody correlations, also the formation of light clusters as deuterons, or particularly strongly bound alfa particles, which dissolve with increasing density due to the Pauli principle, is considered well established in the thermodynamical properties and isotopic composition of the subsaturated matter.
A consistent description of light clusters at low densities and the formation of heavy fragments through spinodal instabilities within the same theoretical approach is however still missing nowadays. In this talk, we propose then a novel approach to include light clusters degrees of freedom within a nonrelativistic kinetic theory based on energy density functionals, providing a unified dynamical framework to account at once for both phenomena, when out of equilibrium processes, as they occur in nuclear reactions, are considered. Implications for general aspects of reactions dynamics and in the widest scope of astrophysical applications are envisaged and will be discussed.
The study of reactions involving weaklybound exotic nuclei is an active field due to advances in radioactive beam facilities. Many of these nuclei can be approximately described by a model consisting of an inert core and one or more valence nucleons. For some of these nuclei, the quadrupole deformation is especially relevant and should be included in the structure models. This is the case of $^{11}\text{Be}$ and $^{17}\text{C}$, which can be approximately described as a core and a weaklybound neutron. In order to include the effect of the deformation in these two nuclei, two different models have been used: the semimicroscopic particleplusAMD (PAMD) model from [Phys. Rev. C 89 (2014) 014333] and the Nilsson model.
The bound and unbound states wavefunctions obtained with both models have been tested by comparing with experimental data for transfer reactions, using as reaction framework the Adiabatic Distorted Wave Approximation (ADWA). In the case of bound states, by applying them to the transfer reactions $^{11}\text{Be}(p,d)^{10}\text{Be}$ and $^{16}\text{C}(d,p)^{17}\text{C}$ [Phys. Rev. C 108 (2023) 024613]. The results are consistent with the data from [Chinese Phys. Lett. 35 (2018) 082501] and [Nucl. Phys. A 683 (2001) 48] in case of $^{11}\text{Be}(p,d)^{10}\text{Be}$, and with the data from [Phys. Lett. B 811 (2020) 135939] for $^{16}\text{C}(d,p)^{17}\text{C}$.
In our calculations, the continuum spectrum of the weaklybound nuclei is discretized using the transformed harmonic oscillator basis (THO) [Phys. Rev. C 80 (2009) 054605]. This basis has been successfully applied to the discretization of the continuum of twobody and threebody weaklybound nuclei for the analysis of break up and transfer reactions [Phys. Rev. Lett. 109 (2012) 232502, Phys. Rev. C 94 (2016) 054622]. The obtained $^{17}\text{C}$ wavefunctions are applied to transfer reactions populating unbound states as well as to breakup reactions. In particular, the transfer to the continuum in $^{16}\text{C}(d,p)^{17}\text{C}$ is studied, with the motivation of investigating the N=16 shell gap.
We study the shape coexistence in the nucleus $^{28}$Si with the nuclear shell model using numerical diagonalizations complemented with variational calculations based on the projected generatorcoordinate method. The calculated electric quadrupole transitions and moments and an analysis of the collective wavefunctions indicate that the standard USDB interaction in the $sd$ shell describes well the groundstate oblate rotational band, but misses the experimental prolate rotational band.
Guided by the quasiSU(3) model, we show that the prolate band can be reproduced either in the $sd$ shell, but by reducing the energy of the $0d_{3/2}$ orbital, or in the extended $sdpf$ configuration space, by using the SDPFNR interaction which also describes well other Si isotopes. Finally, we address the possibility of superdeformation in $^{28}$Si within the $sdpf$ space. Our results disfavour the appearance of superdeformed states with excitation energy below 20 MeV.
In quantum mechanics the coupling of a particle’s velocity with its own spin is at the origin of the spinorbit effect that creates many fundamental phenomena in mesoscopic systems. In nuclear physics, a sizeable spinorbit interaction, that breaks energy levels with the same
orbital momentum (l) but different spin value (s) apart, is responsible for the observed shell structure and generates the well known sequence of magic numbers [1]. From all the magic numbers that emerge as a consequence of the spinorbit splitting, the gaps at 6 and 14, were already considered by GoepperMayer and Jensen as very weak [1]. Just recently, experimental results published in Nature [2] showed evidence for a Z=6 shell closure. However, a (p,2p) experiment [3] was performed later and supported a moderate reduction of the 1p1/2 and 1p3/2 splitting. Yet not direct measurement of the gap has been obtained so far and therefore direct probes that are sensitive to the singleparticle configurations need to be used in order to shed light on the role of the different forces at play. In this talk, I will present the results from the singleproton removal reaction 20O(d,3 He)19N which aimed at probing the Z=6 shell gap towards the neutron dripline. The goal of the 20O(d,3 He)19N [4] experiment with ACTAR TPC [5–7] at GANIL is twofold: First, the experiment will provide a unique way of determining the gap between the 1p1/2 and 1p3/2 singleparticle states in 19 N and will bring crucial information on the Z=6 shell gap. Second, this experiment is the first transfer experiment with the new generation of active targets. Originally, these transfer experiments required the use of complex arrays for particle and
gamma detection systems to improve selectivity. The use of active targets overcomes the aforementioned difficulties and is specially well adapted to explore new regions of the nuclear chart with unprecedented resolution using a much more compact detection system.
References
[1] M. Goeppert Mayer, Nobel Lectures, Physics, 2037 (1963).
[2] D. T. Tran, H. J. Ong et al., Nature communications 9 (2018) 1594
[3] I. Syndikus et al., Phys. Lett. B 809 (2020) 135748
[4] J. LoisFuentes, Ph. D. USC (2023)
[5] T. Roger et al. Nucl. Instrum. Meth. Phys. Res. A 895, 126 (2018).
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[7] B. Mauss et al. Nucl. Instrum. Meth. Phys. Res. A 940, 498 (2019).
Exquisite experimental measurements over the last two decades have allowed us to precisely extract fundamental parameters of the Standard Model and
to uncover new physics, in the form of nonzero neutrino masses.
These remarkable advances have been made possible by the theoretical foundations in hadronic physics. I will illustrate this on a number of specific examples, including lepton flavour violation,
measurement of the anomalous magnetic moment of the muon
and search for light dark matter. Demands on hadronic physics will only increase in the future,
with flavour violating searches
at the LHC and BELLE II and g2 and mu2e experiments at FermiLab.
We compute for the first time the τ datadriven Euclidean windows for the hadronic vacuum polarization contribution to the muon g−2. We show that τbased results agree with the available lattice window evaluations and with the full result. On the intermediate window, where all lattice evaluations are rather precise and agree, τbased results are compatible with them. This is particularly interesting, given that the disagreement of the e+e− datadriven result with the lattice values in this window is the main cause for their discrepancy, affecting the interpretation of the a_μ measurement in terms of possible new physics.
We examine the compatibility of the different data sets of e^+e^ > pi^+ pi^ and tau^ > pi^ pi^0 nu_tau accounting for the required isospinbreaking between both sources of input to a_mu^{HVP,LO}_{pipi}, which is responsible for the current conundrum in the databased SM prediction of a_mu.
Rare kaon decays are among the most sensitive probes of both heavy and light new physics beyond the Standard Model description thanks to high precision of the Standard Model predictions, availability of very large datasets, and the relatively simple decay topologies. The NA62 experiment at CERN is a multipurpose highintensity kaon decay experiment, and carries out a broad raredecay and hiddensector physics programme. NA62 has collected a large sample of $K^+$ decays in flight during Run 1 in 20162018, and the ongoing Run 2 which started in 2021. Recent NA62 results on searches for hiddensector mediators and searches for violation of lepton number and lepton flavour conservation in kaon decays based on the Run 1 dataset are presented.
In this talk NA62 also reports recent results from precision measurements of rare kaon and pion decays, using data collected in Run 1. A sample of $K^+ \rightarrow \pi^+ \gamma \gamma$ decays was collected using a minimumbias trigger, and the results include measurement of the branching ratio, study of the diphoton mass spectrum, and the first search for production and prompt decay of an axionlike particle with gluon coupling in the process $K^+ \rightarrow \pi^+ A$, $A \rightarrow \gamma \gamma$. A sample of $\pi^0 \rightarrow e^+ e^$ decay candidates was collected using a dedicated scaled down dielectron trigger, and a preliminary result of the branching fraction measurement is presented.
The NA62 experiment can be run as a beamdump" experiment by removing the kaon production target and moving the upstream collimators into a
closed" position.
In this configuration 400~GeV protons are dumped on an absorber and New Physics (NP) particles, including dark photons, dark scalars and axionlike particles, may be produced and reach a decay volume beginning 80~m downstream of the absorber. More than $10^{17}$ protons on target have been collected in "beamdump" mode by NA62 in 2021. Recent results from analysis of this data, with a particular emphasis on Dark Photon and Axionlike particle Models, are presented.
We review the radiative corrections to the tau > P (P) nu_tau [gamma] decays and their implications for several SM tests: lepton universality, CKM unitarity and nonstandard interactions.
Research on hypernuclei plays an essential role in answering how the hierarchy of nuclei is constructed from quarks. We are going to review the recent achievements in hypernuclear programs in JPARC. One of the recent achievements is the realization of an accurate hyperonnucleon scattering experiment. The differential cross sections of the Σ+p, Σ−p elastic scatterings and Σ−p → Λn inelastic scattering have been measured with drastically improved accuracy. These new data will become essential inputs to improve the theories of the twobody baryon baryon interaction. Another achievement is the big progress of research on the double hypernuclei. A lot of information on double Λ hypernuclei and Ξ hypernuclei has been accumulated through the observation of the double hypernuclear events in the nuclear emulsion in the series of experiments at KEK and JPARC. Other experiments to study S=2 system were also carried out and the analysis is ongoing. In this article, the progress of the hypernuclear program in JPARC is presented with a focus on these experimental results. Future prospects are also discussed briefly.
Genuine threebody forces in nuclear physics absorb all the effects which can not be described by twobody interactions in three, four.. body systems and are necessary ingredients in the description of nuclear binding energies. For hyperons and nucleons such forces have never been measured directly since scattering experiments are difficult with unstable hyperons and since the database of hyper nuclei is still limited in comparison to the precision achieved for nuclei. In this talk we will discuss the possibility of measuring threebody interactions for hyperons and nucleons exploiting the femtoscopy method at the LHC. The experimental methodology and the recent results by phenomenological calculations will clarify to which extend the still unknown hyperonnucleonnucleon interactions can be measured in the next years.
The goal of the Muon g2 experiment at Fermilab is to measure the muon magnetic moment anomaly with a final accuracy of 140 parts per billion (ppb). At present the experiment published two results based on the data collected in 2018 (Run1) and 20192020 (Run2/3) respectively. These new results confirm the previous measurement performed at Brookhaven National Laboratory and their combination reaches the unprecedented uncertainty of 200 ppb. This talk will summarize the Run1 and Run2/3 measurement, detailing the improvements in systematic and statistical uncertainties in the latest result, will present an overview of the comparison with the Standard Model prediction for muon g2 and will disuss the future prospects for the experiment.
The scientific foundation for the ElectronIon Collider (EIC) was built over two decades. The EIC will be sited at Brookhaven National Lab and constructed in partnership with Jefferson Lab. The EIC will have a versatile range of beam energies, polarizations, and ion species, as well as high luminosity, to precisely image quarks, gluons, and their interactions in protons and complex atomic nuclei. It will discover how mass and spin are dynamically generated by the interaction of quark and gluon fields inside protons and neutrons. Using its versatility, the EIC can probe deep inside nuclei where structures and dynamics are expected to become dominated by dense systems of gluons, possibly reaching a state of saturation. The overarching EIC goal is an understanding of the internal structure of nuclear matter comparable to our knowledge of the electronic structure of atoms. The EIC construction project is notionally envisioned to be completed in the first part of the next decade. The status of the EIC and the worldwide efforts towards the realization of the ePIC detector will be presented.
A session to discuss postPhD career options in nuclear and hadron physics.