Quark--Diquark Systematics of Baryons and the SU(6)SYMMETRY for Light States

TL;DR

This paper explores the classification of light baryons as quark-diquark systems, applying SU(6) symmetry constraints to resolve discrepancies in the observed masses of certain delta states.

Contribution

It introduces a systematic approach using SU(6) symmetry constraints to better predict the masses of low-lying delta baryons within quark-diquark models.

Findings

Inclusion of SU(6) constraints shifts the delta(5/2^-) state to about 2300 MeV.

The scheme explains the absence of low-mass delta states below 2000 MeV.

Proposes variants of baryon classification consistent with recent experimental data.

Abstract

We continue our attempts to systematize baryons, which are composed of light quarks ($q=u,d$), as quark--diquark systems. The notion of two diquarks is used: (i) $D^{1}_{1}$, with the spin $S_D=1$ and isospin $I_D=1$ and (ii) $D^{0}_{0}$, with $S_D=0$ and $I_D=0$. Here we try to resolve the problem of the low-lying $\Delta(\frac 52^-)$ states: in the last experiments the lightest state is observed at $\ga 2200$ MeV, not at $1900 - 2000$ MeV as it has been stated 20 years ago. We are looking for different systematization variants with the forbidden low-lying $\Delta(\frac 52^-)$ states in the mass region $\la 2000$ MeV. We see that the inclusion of the SU(6) constraints on $qD^{1}_{1}$ states with angular momentum L=1 results in a shift of the lightest $\Delta(\frac 52^-)$ isobar to $\sim 2300$ MeV. The scheme with the SU(6) constraints for low-lying $qD^{1}_{1}$ and $qD^{0}_{0}$ states (with $L=0,1$) is presented in detail here.