Residual Gauge Fixing in Light-Front QCD

TL;DR

This paper demonstrates that fixing residual gauge freedom in light-front QCD with specific boundary conditions results in a trivial vacuum, with nontrivial features arising from asymptotic gauge fields at infinity.

Contribution

It introduces a gauge fixing method in light-front QCD that simplifies the vacuum structure and clarifies the origin of nontrivial topological features.

Findings

Residual gauge freedom is fixed with antisymmetric boundary conditions.

Light-front QCD vacuum is shown to be trivial under these conditions.

Nontrivial topological features originate from asymptotic gauge fields at infinity.

Abstract

Understanding the nontrivial features of light-front QCD is a central goal in current investigations of nonperturbative light-front field theory. We find that, with the choice of light-front gauge with antisymmetric boundary conditions for the field variables, the residual gauge freedom is fixed and the light-front QCD vacuum is trivial. The nontrivial structure in light-front QCD is determined by non-vanishing asymptotic physical (transverse) gauge fields at longitudinal infinity, which are responsible for nonzero topological winding number.