Systematics of the heavy flavor hadronic molecules

TL;DR

This paper provides a unified quark-level framework to describe heavy flavor hadronic molecules, reproduces known states, predicts new ones, and offers insights into their isospin preferences and bottom counterparts.

Contribution

It introduces a quark-level interaction model that unifies the description of various heavy flavor molecular states and predicts new states consistent with experimental data.

Findings

Reproduces observed $P_{cs}$ and $T_{cc}^+$ states.

Predicts a narrow $T_{cc}^{\u2032+}$ state.

Explains isospin preferences of molecular candidates.

Abstract

With a quark level interaction, we give a unified description of the loosely bound molecular systems composed of the heavy flavor hadrons $(\bar{D},\bar{D}^*)$, $(\Lambda_c, \Sigma_c, \Sigma_c^*)$, and $(\Xi_c, \Xi_c^\prime,\Xi_c^*)$. Using the $P_c$ states as inputs to fix the interaction strength of light quark-quark pairs, we reproduce the observed $P_{cs}$ and $T_{cc}^+$ states and predict another narrow $T_{cc}^{\prime+}$ state with quantum numbers $[D^*D^*]_{J=1}^{I=0}$. If we require a satisfactory description of the $T_{cc}^+$ and $P_c$ states simultaneously, our framework prefers the assignments of the $P_{c}(4440)$ and $P_{c}(4457)$ as the $[\Sigma_c\bar{D}^*]_{J=1/2}^{I=1/2}$ and $[\Sigma_c\bar{D}^*]_{J=3/2}^{I=1/2}$ states, respectively. We propose the isospin criterion to explain naturally why the experimentally observed $T_{cc}$, $P_c$, and $P_{cs}$ molecular candidates prefer the lowest isospin numbers. We also predict the loosely bound states for the bottom di-hadrons.