The axial charges of proton within an extended chiral constituent quark model

TL;DR

This study investigates the proton's axial charges using an extended chiral constituent quark model that includes five-quark components, fitting parameters to empirical data and achieving results consistent with experiments.

Contribution

The paper introduces a comprehensive model incorporating all possible five-quark configurations in the proton, providing a detailed calculation of axial charges aligned with experimental observations.

Findings

Probabilities of five-quark components are approximately 30-50%.

Calculated axial charges match experimental data.

Model successfully reproduces quark spin contributions.

Abstract

We have performed a study of the isovector, octet and singlet axial charges of the proton in an extended chiral constituent quark model, where all the possible $uudq\bar{q}$~($q=u,d,s$) five-quark Fock components in the proton wave function are taken into account. The $^3P_0$ quark-antiquark creation mechanism is assumed to account for the transition coupling between three- and five-quark components in proton, and the corresponding transition coupling strength is fixed by fitting the intrinsic sea flavor asymmetry $\bar{d}-\bar{u}$ data for proton. Accordingly, with all the parameters fixed by empirical values, the probabilities of the intrinsic five-quark Fock components in proton wave function should be $\sim30 - 50\%$, which lead to the numerical results for quark spin $\Delta u$, $\Delta d$ and $\Delta s$, as well the axial charges of proton consistent with the experimental data and predictions by other theoretical approaches.