Detection schemes for quantum vacuum diffraction and birefringence

TL;DR

This paper calculates the birefringent scattering of x-rays in combined laser fields to aid experimental detection of quantum vacuum effects, emphasizing scenarios with maximal photon differences for clearer signals.

Contribution

It provides theoretical calculations and comparisons of different experimental scenarios for detecting quantum vacuum birefringence with x-ray scattering.

Findings

Maximized differences between initial and final x-ray photons enhance detection signals.

Scattering angles are in the milliradian regime, aiding experimental distinguishability.

Various laser configurations are compared for optimal birefringence detection.

Abstract

Motivated by recent experimental initiatives, such as at the Helmholtz International Beamline for Extreme Fields (HIBEF) at the European X-ray Free Electron Laser (XFEL), we calculate the birefringent scattering of x-rays at the combined field of two optical (or near-optical) lasers and compare various scenarios. In order to facilitate an experimental detection of quantum vacuum diffraction and birefringence, special emphasis is placed on scenarios where the difference between the initial and final x-ray photons is maximized. Apart from their polarization, these signal and background photons may differ in propagation direction (corresponding to scattering angles in the mrad regime) and possibly energy.