Electrodynamics in the presence of an axion

TL;DR

This paper explores how axion fields influence electrodynamics by analyzing gauge field behavior and propagators in various axionic backgrounds, revealing that short-distance gauge propagation remains well-defined.

Contribution

It provides a detailed calculation of the effective action and propagator behavior for axion-coupled gauge fields, including asymptotic solutions for massive axions.

Findings

Short distance gauge propagation is well-defined in generic axionic backgrounds.

The effective action for the axion field is computed at one loop level.

Asymptotic expansion of the causal propagator for a linearly growing axion field.

Abstract

The low energy limit of an axion field coupled to gauge fields is investigated through the behaviour of the gauge field propagator in a local vaccum angle background. The local (singular) part of the effective action for the axion field is calculated at one loop level. In the case of a timelike, linearly growing axion field, representing a massive axion, we give an asymptotic expansion of the causal propagator and we solve nonlocally for the first coefficient. We show that, for a generic axionic background, short distance propagation of the gauge fields is well defined.