Exploration of a physical picture for the QCD scalar channel

TL;DR

This paper uses a generalized linear sigma model to investigate the quark composition of low-lying scalar and pseudoscalar mesons, revealing significant four-quark components in scalars and mainly quark-antiquark structure in pseudoscalars.

Contribution

It introduces a model that allows mixing of different quark configurations without prior assumptions, incorporating SU(3) symmetry breaking effects.

Findings

Light pseudoscalars are mainly quark-antiquark states.

Light scalars have large four-quark admixtures.

Model provides a unified framework for meson quark structure analysis.

Abstract

A generalized linear sigma model is employed to study the quark structure of low lying scalar as well as pseudoscalar states. The model allows the possible mixing of quark anti-quark states with others made of two quarks and two antiquarks but no a priori assumption is made about the quark contents of the predicted physical states. Effects of SU(3) symmetry breaking are included. The lighter conventional pseudoscalars turn out to be primarily of two quark type whereas the lighter scalars have very large four quark admixtures.