Pentaquarks made of light quarks and their admixture to baryons

TL;DR

This paper extends previous methods to analyze light pentaquark states, exploring their wavefunctions, mixing with baryons, and implications for nucleon properties and flavor asymmetry in the quark sea.

Contribution

It develops a group-theoretic method to explicitly construct wavefunctions for light pentaquarks and studies their mixing with baryons via quark-antiquark pairs.

Findings

Wavefunctions for light pentaquarks in S- and P-shells derived.

Pentaquark-baryon mixing influences nucleon properties.

Insights into flavor asymmetry of the antiquark sea obtained.

Abstract

This paper is a continuation of our studies of multiquark hadrons. The anti-symmetrization of their wavefunctions required by Fermi statistics is nontivial, as it mixes orbital, color, spin and flavor structures. In our previous papers we developed a method to find them based on the representations of the permutation group, and derived the explicit wave functions for baryons excited to the first and second shells $(L=1,2)$, tetraquarks $qq\bar q\bar q$ and hexaquarks ($6q$). Now we apply it to light pentaquarks ($qqqq\bar q$), in the S- and P-shells ($L=0,1$). Using Jacobi coordinates, one can use the hyperdistance approximation in 12-dimensional space. We further address the issue of ``unquenching" of baryons, by considering their mixing with pentaquarks, via two channels, through the addition of $\sigma$-like or $\pi$-like $\bar q q$ pairs. This mixing is central for understanding of the observed flavor asymmetry of the antiquark sea, the amount of orbital motion issue as well as other nucleon properties.