Consistent gauge invariant nucleon spin decomposition

TL;DR

This paper addresses the non-uniqueness in gauge invariant nucleon spin decomposition by proposing a consistent scheme that separates gluon contributions and aligns with helicity concepts in non-Abelian gauge theories.

Contribution

It introduces a gauge invariant decomposition with a generalized Coulomb constraint and an explicit Abelian projection, advancing the understanding of gluon contributions in nucleon spin.

Findings

Constructed a gauge invariant nucleon spin decomposition scheme.

Provided an explicit representation for gauge invariant Abelian projection.

Demonstrated consistency with helicity in non-Abelian gauge theory.

Abstract

We consider a non-uniqueness problem of gauge invariant nucleon spin decomposition. A gauge invariant decomposition with a generalized Coulomb constraint for the physical gluon has been constructed. The decomposition scheme is consistent with the concept of helicity in non-Abelian gauge theory. We provide an explicit representation for the gauge invariant Abelian projection which implies further separation of gluon into binding and valence parts.