Low-Energy Compton Scattering in Materials

TL;DR

This paper introduces a new method to accurately calculate low-energy Compton scattering in materials by relating it to dielectric response, improving predictions for experiments searching for dark matter and other particles.

Contribution

It develops a comprehensive approach that incorporates all-electron, band structure, and collective effects for low-energy Compton scattering calculations in various materials.

Findings

The method accurately predicts scattering in Si, Ge, GaAs, and SiC.

It improves background modeling for dark matter detection experiments.

The approach is applicable to a wide range of materials.

Abstract

Low-energy Compton scattering is an important background for sub-GeV dark matter direct-detection and other experiments. Current Compton scattering calculations typically rely on assumptions that are not valid in the low-energy region of interest, beneath ~ 50 eV. Here we relate the low-energy Compton scattering differential cross section to the dielectric response of the material. Our new approach can be used for a wide range of materials and includes all-electron, band structure, and collective effects, which can be particularly relevant at low energies. We demonstrate the strength of our approach in several solid-state systems, in particular Si, Ge, GaAs, and SiC, which are relevant for current and proposed experiments searching for dark matter, neutrinos, and millicharged particles.