Dynamical bag in a chiral quark model

TL;DR

This paper introduces a dynamical bag model for baryons where the bag surface is made flexible, leading to improved predictions of proton properties by incorporating chiral symmetry and nonlinear pion interactions.

Contribution

It proposes a novel dynamical bag function in a chiral quark model, connecting chiral symmetry breaking with baryon structure predictions.

Findings

Predicted bag constant B ≈ 2f_π^2 m_π^2

Calculated proton mass, radius, and magnetic moment agree with experimental data

Model incorporates nonlinear pion background and dynamical bag surface

Abstract

A type of bag function is proposed to make the MIT bag surface of baryon dynamical. It is illustrated through renormalization of the quark field that the softening of chiral bag gives rise to a model of chiral quark with effectively-generated mass of quark, in which confined quark moves in the background of nonlinear pion. A prediction of bag constant $B$ $\simeq 2f_{\pi}^{2}m_{\pi}^{2}\allowbreak $ is made. With two free parameters, the self-coupling $e$ of pion and the confining scale $a$, the computed mass, the charge root-mean-square radius and magnetic moment of the proton are in good agreement with the experimental values.