Field-assisted birefringent Compton scattering

TL;DR

This paper investigates how strong external fields influence x-ray Compton scattering, focusing on polarization changes, which could serve as diagnostic tools or background signals in high-field physics experiments.

Contribution

It provides a theoretical analysis of birefringent effects in Compton scattering under strong fields, highlighting their potential for diagnostics and experimental background understanding.

Findings

Birefringent contribution vanishes without external field in forward direction.

The ratio of birefringent to normal scattering reveals the field strength.

Potential application in high-field experimental diagnostics.

Abstract

Motivated by experimental initiatives such as the Helmholtz International Beamline for Extreme Fields (HIBEF), we study Compton scattering of x-rays at electrons in a strong external field (e.g., a strong optical laser) with special emphasis on the polarization-changing (i.e., birefringent) contribution on the amplitude level. Apart from being a potential background process for the planned vacuum birefringence experiments, this effect could be used for diagnostic purposes. Since the birefringent signal from free electrons (i.e., without the external field) vanishes in forward direction, the ratio of the birefringent and the normal (polarization conserving) contribution yields information about the field strength at the interaction point.