A possible interpretation of $\Lambda$ baryon spectrum with pentaquark components

TL;DR

This paper explores the $ ext{Lambda}$ baryon spectrum using a constituent quark model, proposing that certain negative-parity resonances are mixtures of three-quark states and pentaquark components, offering a new interpretation.

Contribution

It introduces a novel interpretation of $ ext{Lambda}$ resonances as mixtures of three-quark and pentaquark states within a constituent quark model.

Findings

Negative-parity $ ext{Lambda}$ resonances are difficult to explain as pure three-quark states.

Proposes that observed resonances are three-state mixtures of $q^2s$ and $q^3sar q$ configurations.

Provides a mass spectrum evaluation supporting the pentaquark component hypothesis.

Abstract

The $\Lambda$ baryon spectrum is studied within the SU(3) flavor symmetry in a constituent quark model. We found that it is rather difficult to accommodate some negative-parity $\Lambda$ resonances as single $q^2s$ ($q = u,\,d$ quarks) states in the conventional three-quark picture. The ground $q^3s\bar q$ pentaquark mass spectrum is evaluated and a possible interpretation is proposed in the work: the observed $\Lambda(1405)1/2^{-}$, $\Lambda(1670)1/2^{-}$ and $\Lambda(1800)1/2^{-}$ are three-state mixtures of two $p$-wave $q^2s$ states and one ground $q^3s\bar q$ pentaquark state, so are the $\Lambda(1520)3/2^{-}$, $\Lambda(1690)3/2^{-}$ and $\Lambda(2050)3/2^{-}$ resonances.