The simplest description of charge propagation in a strong background

TL;DR

This paper introduces a novel gauge choice in the Volkov description that simplifies charge propagation in plane wave backgrounds, providing a compact propagator and insights into gauge artefacts and renormalisation.

Contribution

It presents a new gauge fixing method that simplifies the propagator for scalar and fermionic charges in plane wave backgrounds, revealing gauge artefacts and analyzing ultraviolet behaviour.

Findings

Many observed structures are gauge artefacts.

A compact propagator for scalar and fermionic matter is developed.

Different renormalisation prescriptions are identified for scalar and fermionic charges.

Abstract

Exploiting the gauge freedom associated with the Volkov description of a charge propagating in a plane wave background, we identify a new type of gauge choice which significantly simplifies the theory. This allows us to develop a compact description of the propagator for both scalar and fermionic matter, in a circularly polarised background. It is shown that many of the usually observed structures are gauge artefacts. We then analyse the full ultraviolet behaviour of the one-loop corrections for such charges. This enables us to identify and contrast the different renormalisation prescriptions needed for both types of matter.