Coherence from Randomness: Sub-keV Dark Matter Scattering off Random, Heterogeneous Materials

TL;DR

This paper proposes a novel detection mechanism for sub-keV dark matter using random heterogeneous materials, leveraging intrinsic density fluctuations to enhance scattering signals and extend experimental constraints.

Contribution

It introduces a new scattering mechanism involving random materials and derives novel constraints on sub-keV dark matter from MICROSCOPE data.

Findings

Enhanced scattering rate due to density fluctuations.

Extended constraints on dark matter cross sections.

Potential for measurable accelerations of targets.

Abstract

The sub-keV mass range has long posed a challenge for the direct detection of dark matter via elastic scattering. In this Letter, we propose a new mechanism in which dark matter, assumed to be quadratically coupled to SM particles, scatters from random heterogeneous materials with intrinsic density fluctuations, yielding an enhanced coherent response. This effect can substantially increase the total scattering rate and induce measurable accelerations of the target. Using this idea, we derive new constraints from the MICROSCOPE mission that extend into previously unexplored parameter space for sub-keV dark matter, probing cross sections down to $\sim 4\times10^{-38}\,\mathrm{cm^2}$.