Ellipticity induced in vacuum birefringence

TL;DR

This paper investigates how ellipticity signals in vacuum birefringence experiments relate to photon polarization flip amplitudes, especially for realistic laser fields, advancing understanding of photon-photon scattering detection.

Contribution

It extends the ellipticity-flip amplitude relation from plane waves to more realistic laser field configurations.

Findings

Ellipticity equals flip amplitude for plane wave backgrounds.

The relation between ellipticity and flip amplitude is modified for realistic fields.

Provides insights for designing experiments to detect vacuum birefringence.

Abstract

We consider signals of photon-photon scattering in laser-based, low energy experiments. In particular, we consider the ellipticity induced on a probe beam by a strong background field, and compare it with a recent worldline expression for the photon polarisation flip amplitude. When the probe and the background are plane waves, the ellipticity is equal to the flip amplitude. Here we investigate the ellipticity-amplitude relation for more physical fields.