Group theoretical study of nonstrange and strange mixed symmetric baryon states $[N_c-1,1]$ in the $1/N_c$ expansion

TL;DR

This paper derives exact SU(6) wave functions for mixed symmetric baryon states in the 1/Nc expansion, enabling detailed study of strange and nonstrange baryon spectra and comparing exact versus approximate wave functions.

Contribution

It extends previous work by providing complete SU(6) wave functions for mixed symmetric states, allowing for accurate analysis of baryon spectra including strange baryons.

Findings

Exact wave functions yield consistent asymptotic flavor operator matrix elements at large N_c.

Approximate wave functions fail to reproduce the same asymptotic behavior.

Derived isoscalar factors applicable to fermion systems with partition [N_c-1,1].

Abstract

Using group theory arguments we extend and complete our previous work by deriving all SU(6) exact wave functions associated to the spectrum of mixed symmetric baryon states $[N_c-1,1]$ in the $1/N_c$ expansion. The extension to SU(6) enables us to study the mass spectra of both strange and nonstrange baryons, while previous work was restricted to nonstrange baryons described by SU(4). The wave functions are specially written in a form to allow a comparison with the approximate, customarily used wave functions, where the system is separated into a ground state core and an excited quark. We show that the matrix elements of the flavor operator calculated with the exact wave functions acquire the same asymptotic form at large $N_c$, irrespective of the spin-flavor multiplet contained in $[N_c-1,1]$, while with the approximate wave function one cannot obtain a similar behaviour. The isoscalar factors of the permutation group of $N_c$ particles derived here can be used in any problem where a given fermion system is described by the partition $[N_c-1,1]$, and one fermion has to be separated from the rest.