Radiatively Induced Lorentz and CPT Violation in Schwinger Constant Field Approximation

TL;DR

This paper uses the Schwinger proper-time method to analyze how axial vector interactions in quantum electrodynamics can induce Lorentz and CPT violation, revealing scheme-dependent differences in the resulting Chern-Simons term.

Contribution

It demonstrates the radiative induction of Lorentz and CPT violation using a gauge-invariant, nonperturbative approach, highlighting regularization scheme ambiguities.

Findings

Induced Chern-Simons term matches covariant derivative expansion results.

Results differ from those obtained in other regularization schemes.

Discussion of potential ambiguities in the calculation approach.

Abstract

The Schwinger proper-time method is an effective calculation method, explicitly gauge invariant and nonperturbative. We make use of this method to investigate the radiatively induced Lorentz and CPT-violating effects in quantum electrodynamics when an axial vector interaction term is introduced in the fermionic sector. The induced Lorentz and CPT-violating Chern-Simons term coincides with the one obtained using a covariant derivative expansion but differs from the result usually obtained in other regularization schemes. A possible ambiguity in the approach is also discussed.