The contributions of $qqqq\bar{q}$ components to the axial charges of proton and its resonances

TL;DR

This paper extends the constituent quark model to include $qqqq\bar{q}$ components, improving the theoretical prediction of proton axial charges and predicting a unity axial charge for $N^{*}(1440)$.

Contribution

It introduces $qqqq\bar{q}$ components into the constituent quark model to better match empirical axial charge values of the proton and resonances.

Findings

Including 20% $qqqq\bar{q}$ components aligns the model with empirical axial charge of proton.

Predicts an axial charge of one for $N^{*}(1440)$ with 30% $qqqq\bar{q}$ admixture.

Traditional models cannot reproduce the axial charge without these components.

Abstract

We calculate the axial charges of the proton and its resonances in the framework of the constituent quark model, which is extended to include the $qqqq\bar{q}$ components. If 20% admixtures of the $qqqq\bar{q}$ components in the proton are assumed, the theoretical value for the axial charge in our model is in good agreement with the empirical value, which can not be well reproduced in the traditional constituent quark model even though the $SU(6) \bigotimes O(3)$ symmetry breaking or relativistic effect is taken into account. We also predict an unity axial charge for $N^{*}(1440)$ with 30% $qqqq\bar{q}$ components constrained by the strong and electromagnetic decays.