Heavy-flavor hadrons with non-conventional 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, open-flavor, double
heavy-flavor, and full heavy-flavor states. Interpretations of these
states vary, ranging from tightly-bound...
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 two-hadron thresholds, a compact or even virtual state interpretation have yet to be completely ruled out. In addition, a purely-kinematic rescattering mechanism involving a...
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...
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...
I will discuss the recent progress in understanding photo production of hybrid mesons
High-statistics total cross-sections 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 โyoungโ vector meson hypothesis may explain the fact...
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...
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 vector-pseudoscalar amplitudes, which can describe the contribution of individual amplitudes to the total...
Exploring the light-quark mass dependence of near-threshold 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 left-hand cuts originating from long-range interactions, thereby...
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...
When two particles form a nearly resonant bound state due to short-range attractive forces, an effective long-range three-body emerges giving rise to an infinite number of three-body 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...
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...
The Belle and Belle$~$II experiments have collected a $1.4~\mathrm{ab}^{-1}$ sample of $e^+e^-$ collision data at centre-of-mass 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...
A search for the $H$-dibaryon has been conducted at J-PARC 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 time-projection chamber (HypTPC) reconstructs all charged particles' trajectories that emerged from the $^{12}$C$(K^-,...
The existence of exotic multi-quark states beyond the conventional valence three quark and quark-antiquark systems has been unambiguously confirmed in the heavy quark sectors. Such states could manifest as single colour bound objects, or evolve from meson-baryon and meson-meson interactions, creating molecular like systems and re-scattering effects near production thresholds. Equivalent...
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,...
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 Einstein-dilaton 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:...
Using the worldโs 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...
A precise description of pion-pion 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 G-waves, the study of Forward Dispersion Relations (FDRs) up to 1.6 GeV, and data...
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...
One of the earliest predictions of Quantum Chromodynamics (QCD) is the existence of color singlet pure-gauge states known as glueballs. However, despite this anticipation, consensus on their theoretical properties and experimental evidence remains elusive. Two-gluon glueball states have been quite abundantly explored both theoretically and experimentally. One may cite, for example, on the...
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...
