Investigation of $qqqs\bar q$ pentaquarks in a chiral quark model

TL;DR

This study explores $qqqsar q$ pentaquark states using a chiral quark model, identifying several resonance states with potential relevance to known hyperons and their structures.

Contribution

It introduces a comprehensive analysis of pentaquark configurations considering all color, spin, and flavor states within a chiral quark framework, highlighting possible resonance states.

Findings

Identification of resonance states like $ ext{N}ar{ ext{K}}$ and $ ext{Sigma} ext{pi}$ with specific quantum numbers.

The $Nar{K}$ state explains the $ ext{Lambda}(1405)$ structure.

Most other states have large decay widths.

Abstract

We investigate the pentaquark system $qqqs \bar q$ in a framework of chiral quark model. Two structures, $(qqq)(s\bar{q})$ and $(qqs)(q\bar{q})$, with all possible color, spin, flavor configurations are considered. The calculations show that there are several possible resonance states, $Sigma \pi$ and $N \bar{K}$ state with $IJ^P=0\frac{1}{2}^-$, $\Sigma^* \pi$ with $IJ^P=0\frac{3}{2}^-$, $\Sigma^* \rho$ with $IJ^P=0\frac{5}{2}^-$, $\Delta \bar{K}$ with $IJ^P=1\frac{3}{2}^-$ and $\Delta \bar{K}^*$ with $IJ^P=1\frac{5}{2}^-$. Where the $N \bar{K}$ state with $IJ^P=0\frac{1}{2}^-$ can be used to explain the $\Lambda(1405)$, and together with another state $\Sigma\pi$ is related to the two-pole structure of the scattering amplitude proposed before. The decay properties of $\Lambda(1520)$ prevent the assignment of $\Sigma^* \pi$ with $IJ^P=0\frac{3}{2}^-$ to $\Lambda(1520)$, although the energy $\sim$ 1518 MeV of $\Sigma^* \pi$ is close to experimental value of $\Lambda(1520)$. Other resonance states generally have a large width.