Compact hidden charm pentaquark states and QCD isomers

TL;DR

This paper investigates the structure and properties of hidden charm pentaquark states using a multiquark color flux-tube model, revealing novel configurations and predicting new states with specific spin-parity and color structures.

Contribution

It introduces a comprehensive multiquark flux-tube model to describe pentaquark states, highlighting the role of color structures and QCD isomers in their formation and properties.

Findings

Describes pentaquark states as compact structures with specific color configurations.

Identifies QCD isomers with identical quantum numbers but different color structures.

Predicts new pentaquark families such as $P_{cs}$, $P_{c ss}$, and $P_{csss}$.

Abstract

We make an exhaustive investigation on the pentaquark states $qqqc\bar{c}$ ($q=u, d$ and $s$) and discuss the effect of color structures in a multiquark color flux-tube model. We exhibit a novel picture of the structure and properties of the states $P_c$ and $P_{cs}$ observed by the LHCb Collaboration. We can describe the states as the compact pentaquark states in the model. The spin-parity of the group of $P_c(4312)^+$ and $P_c(4337)^+$ is $\frac{1}{2}^-$ while that of the group of $P_c(4380)^+$, $P_c(4440)^+$ and $P_c(4457)^+$ is $\frac{3}{2}^-$. Their structures are pentagon, diquark, pentagon, diquark, and octet, respectively. The members in each group can be analogically called QCD isomers because of their the same spin-parity and quark content but different color structures. The singlet $P_{cs}(4459)^0$ has pentagon structure and spin-parity of $\frac{1}{2}^-$. In addition, we also predict the $P_{cs}$, $P_{c ss}$ and $P_{csss}$ families in the model. The five-body confinement potential based on the color flux-tube picture, which is a collective degree of freedom and induces QCD isomer phenomenon, plays an important role in the formation of the compact states.