Speaker
Description
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 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 three-body bound states and its low-energy universality in the charm and bottom sectors has been explored in the recent literature, specially since the discovery of the $X(3872)$ state, a loosely-bound $D^{*\,0}\bar D^0$+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 $(I)J^P=(\frac{1}{2})0^-$ three-body 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), 563-564.
[2] T. Kraemer, Nature 440, Issue 7082, pp. 315-318 (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, 751-754.
[5] P.G. Ortega, arXiv:2403.10244 [hep-ph].
| session | B. Hadron Spectroscopy |
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