Infra-red divergences in plane wave backgrounds

TL;DR

This paper investigates infra-red divergences in soft photon emission during nonlinear Compton scattering in pulsed plane wave laser fields, highlighting classical and quantum cases with specific focus on crossed fields.

Contribution

It provides a detailed analysis of infra-red divergences in nonlinear Compton scattering within pulsed plane wave backgrounds, including classical and quantum perspectives, and examines crossed field scenarios.

Findings

Infra-red divergences occur in soft photon emission in pulsed plane wave backgrounds.

Both soft and soft-collinear divergences are identified and analyzed.

Crossed fields exhibit particular behaviors in classical and quantum regimes.

Abstract

We show that the emission of soft photons via nonlinear Compton scattering in a pulsed plane wave (laser field) is in general infra-red divergent. We give examples of both soft and soft-collinear divergences, and we pay particular attention to the case of crossed fields in both classical and quantum theories.