Vacuum polarisation effects in impulsive fields

TL;DR

This paper studies how quantum vacuum polarisation affects photon behavior in impulsive electromagnetic fields, revealing connections to vacuum birefringence, quantum reflection, and loop corrections in QED and SUSY QED.

Contribution

It provides a detailed analysis of vacuum polarisation effects in impulsive fields and compares these with known results in plane wave backgrounds, extending understanding to one-loop corrections.

Findings

Vacuum birefringence and quantum reflection are characterized in impulsive fields.

Loop corrections modify known tree-level amplitude relations.

Results connect quantum effects in impulsive fields with established phenomena in QED and SUSY QED.

Abstract

Photons impinging on strong electromagnetic fields can change both momentum and helicity state, due to quantum vacuum polarisation. We investigate these effects in the collision of photons with impulsive PP-waves, which describe e.g. the fields of ultra-boosted charge distributions. We connect our results to vacuum birefringence and quantum reflection in both QED and SUSY QED. We also compare with helicity flip in plane wave backgrounds, exploring how and when known tree-level relations, relating amplitudes in PP-waves and in plane waves, extend to one-loop corrections.