Baryons 2022 - International Conference on the Structure of Baryons

Hidden-charm PψsΛ pentaquarks in a constituent quark model calculation

Not scheduled

20m

Seville

Parallel contribution Hadron-hadron interactions

Speaker

Dr Pablo G. Ortega (University of Salamanca)

Description

The discovery of pentaquark states by the LHCb [1] revolutionized Hadron Physics, expanding the usual $qqq$ structure to four quarks and an antiquark. The first observations, detected in the $J/\psi p$ mass spectrum, showed two resonances, dubbed $P_c(4380{)}^{+}$ and $P_c(4450{)}^{+}$, close to $D^{(\ast )}N$ thresholds, which suggested a baryon-meson molecular nature in contrast to a compact pentaquark core. The existence of such pentaquarks, with minimum $\overline{c}cuud$ quark content, anticipated similar hidden-charm structures with strangeness, i.e., with $\overline{c}cuds$, which were recently confirmed with the discovery of the so-called $P_{cs}(4459{)}^0$ [2], now called $P_{\psi s}^{\mathrm{\Lambda }}(4459{)}^0$.

In this work, we provide a theoretical description of the $P_{\psi s}^{\mathrm{\Lambda }}(4459{)}^0$ and $P_{\psi s}^{\mathrm{\Lambda }}(4338)$ resonances as ${\overline{D}}^{(\ast )}{\mathrm{\Xi }}_c^{(\prime )(\ast )}$ molecular states in the framework of a constituent quark model that has been extensively used to describe hadron phenomenology [3], in particular exotic states in the baryon spectrum as meson-baryon molecules [4,5]. Such $P_{\psi s}^{\mathrm{\Lambda }}$ states are found in the $J^P={\frac{1}{2}}^{-}$ channel with masses and widths compatible with the experimental measurements in a coupled-channels calculation with all the parameters constrained from previous studies. Other candidates are explored in the $J^P={\frac{3}{2}}^{-}$ and ${\frac{5}{2}}^{-}$ channels. Additionally, $P_{\psi ss}^N$ pentaquark states are predicted as ${\overline{D}}_s{\mathrm{\Xi }}_c$ molecules.

[1] R. Aaij et al. [LHCb], Phys. Rev. Lett. 115 (2015), 072001.
[2] R. Aaij et al. [LHCb], Sci. Bull. 66 (2021),1278-1287.
[3] J. Vijande, F. Fernandez and A. Valcarce, J. Phys. G 31 (2005), 481.
[4] P. G. Ortega, D. R. Entem and F. Fernandez, Phys. Lett. B 718 (2013),
1381-1384.
[5] P. G. Ortega, D. R. Entem and F. Fernández, Phys. Lett. B 764 (2017),
207-211.

Presentation materials

OrtegaPG-Pcs.pdf