Residual gauge-invariance in a massive Lorentz-violating extension of QED

TL;DR

This paper investigates a CPT-odd electrodynamics model derived via a Palatini-like approach, revealing residual gauge invariance under specific conditions and analyzing its physical consistency across parameter values.

Contribution

It demonstrates the existence of residual gauge invariance in a Lorentz-violating massive QED extension, extending understanding of gauge symmetry breaking mechanisms.

Findings

Residual gauge invariance exists when transformations vary along the Lorentz-breaking vector.

The model remains physically consistent for certain parameter ranges.

Residual gauge invariance can be generalized to similar models with mass-term-induced symmetry breaking.

Abstract

We reassess an alternative CPT-odd electrodynamics obtained from a Palatini-like procedure. Starting from a more general situation, we analyze the physical consistency of the model for different values of the parameter introduced in the mass tensor. We show that there is a residual gauge-invariance in the model if the local transformation is taken to vary only in the direction of the Lorentz-breaking vector. This residual gauge-invariance can be extended to all models whose only source of gauge symmetry breaking is such a mass term.