Lorentz and CPT Violating Chern-Simons Term in the Derivative Expansion of QED

TL;DR

This paper computes the one-loop effective action in Lorentz-violating QED, demonstrating how a CPT-odd term induces a Chern-Simons modification to Maxwell theory using dimensional regularization.

Contribution

It provides a detailed calculation of the Chern-Simons term induced by Lorentz and CPT violation in QED through derivative expansion and dimensional regularization.

Findings

Induces a Chern-Simons term in Maxwell theory

Uses dimensional regularization for effective action calculation

Clarifies the role of Lorentz-violating terms in gauge theories

Abstract

We calculate by the method of dimensional regularization and derivative expansion the one-loop effective action for a Dirac fermion with a Lorentz-violating and CPT-odd kinetic term in the background of a gauge field. We show that this term induces a Chern-Simons modification to Maxwell theory. Some related issues are also discussed.