Nucleon Electromagnetic and Axial Form Factors in a Light-front Constituent Quark Model

TL;DR

This paper investigates how scalar spin coupling of constituent quarks affects nucleon electroweak properties using a light-front wave function with one or two momentum scales, achieving good agreement with experimental data.

Contribution

It introduces a two-scale light-front wave function model that better describes static observables and form factor ratios compared to a one-scale model.

Findings

Two-scale model reproduces the zero of the form factor ratio around 10 GeV/c^2

Best axial-vector coupling results match neutron magnetic moment data

Model provides a reasonable description of nucleon static properties

Abstract

In the present work we study the effect of the scalar spin coupling of constituent quarks on the nucleon electroweak properties by introducing a valence light-front wave function with two momentum scales. By comparing the results obtained with the one scale and two scale wave function models, we have found that the last one has shown a reasonable description of the static observables and $\mu_pG_{Ep}/G_{Mp}$ ratio in which the position of the zero appears around 10~[GeV/c]$^2$ or for higher squared momentum transfers. We have also shown results for the axial-vector coupling $g_{A}$ and the nucleon axial-vector form factor. The best result for $g_A$ was obtained when the parameters of the nucleon wave function model were such that the experimental value of the neutron magnetic moment was described.