On the definition of the nucleon axial charge density

TL;DR

This paper derives spatial distributions of the nucleon axial charge density for spin-1/2 systems in various Lorentz frames, clarifying their interpretation and examining the static approximation commonly used.

Contribution

It provides a detailed derivation of axial charge density distributions in arbitrary Lorentz frames and discusses their physical interpretation, extending beyond the static approximation.

Findings

Derived spatial distributions in arbitrary Lorentz frames.

Analyzed the static approximation and its implications.

Clarified the physical interpretation of axial charge densities.

Abstract

We work out the spatial density distributions corresponding to the axial-vector charge density operator for spin-1/2 systems using states described by sharply localized wave packets in arbitrary Lorentz-frames. The static approximation, leading to the frequently assumed Breit-frame distributions, is also considered. We discuss the interpretation of the resulting spatial densities in terms of the axial charge density.