Effective Strange Quark/Antiquark Masses from the Chiral Soliton Models for Baryons

TL;DR

This paper estimates effective strange quark and antiquark masses using the chiral soliton approach, discusses their relation to quark models, and emphasizes the importance of configuration mixing and the potential existence of pentaquark states.

Contribution

It provides a detailed comparison between CSA and quark models for baryon spectra, highlighting the effective masses and the role of SU(3) multiplet dependence.

Findings

Effective strange quark mass ~130-135 MeV in CSA predictions.

CSA and quark models agree for pentaquark spectra in certain sectors.

SU(3) configuration mixing influences the effective masses and spectrum predictions.

Abstract

The effective strange quark and antiquark masses are estimated from the chiral soliton approach (CSA) results for the spectrum of exotic and nonexotic baryons. There are problems when one tries to project results of the CSA on the simple quark models (QM): the parameter in $1/N_c$ expansion is so large for the case of the baryon spectrum that extrapolation to the real $N_c=3$ world is not possible; rigid (as well soft) rotator model and the bound state model coincide in the first two orders in $1/N_c$, but differ in the next orders. There is correspondence of the CSA and simple QM predictions for pentaquarks (PQ) spectra in negative $S$ sector of the $\{27\}$ and $\{35\}$-plets: the effective mass of strange quark is about $135 -130\,MeV$, slightly smaller for $\{35\}$. For positive strangeness components the link between CSA and QM requires strong dependence of the effective $\bar{s}$ mass on particular SU(3) multiplet. The SU(3) configuration mixing is important, it pushes the spectrum towards the simplistic model (with equal masses of the strange quark and antiquark), and explanation of this nice property is lacking still. The success of the CSA in describing many properties of baryons and light nuclei (hypernuclei) means that predictions of pentaquark states should be considered seriously. Existence of PQ by itself is without any doubt, although very narrow PQ may not exist. Wide, even very wide PQ should exist, therefore, searches for PQ remain to be an actual task.