Propagation in an intense background

TL;DR

This paper develops a canonical quantisation framework for a charged particle in intense laser backgrounds, deriving the two-point function, causal propagator, and spectral properties, including multi-pole structures, for both circular and linear polarizations.

Contribution

It introduces a comprehensive quantisation method and calculates the propagator and renormalisations in intense laser backgrounds, extending previous approaches.

Findings

Derived the two-point function and causal propagator.

Identified multi-pole structures in the spectral properties.

Calculated wave-function renormalisations to all orders.

Abstract

The canonical quantisation of a charged particle in an intense laser background is developed and the associated two-point function calculated. It is shown how the causal propagator can be extracted. We provide an interpretation of this propagator in terms of degenerate quantum processes. The spectral properties of the propagator are derived and we show how multi-pole structures emerge as a perturbative feature. We also calculate the associated multiple wave-function renormalisations to all orders in perturbation theory. Our calculations are for both circular and linearly polarised plane wave laser backgrounds.