# Terrestrial Effects on Dark Matter-Electron Scattering Experiments

## TL;DR

This paper investigates how Earth's material affects dark matter-electron scattering experiments, revealing significant reductions in sensitivity for current detectors and providing updated mass and cross section constraints for sub-GeV dark matter.

## Contribution

It provides a detailed analysis of terrestrial stopping effects on dark photon dark matter models, updating experimental sensitivity limits and implications for future searches.

## Key findings

- XENON10 excludes dark matter masses between 5-3000 MeV.
- DAMIC probes dark matter masses between 20-50 MeV.
- Terrestrial effects significantly reduce detection sensitivity.

## Abstract

A well-studied possibility is that dark matter may reside in a sector secluded from the Standard Model, except for the so-called photon portal: kinetic mixing between the ordinary and dark photons. Such interactions can be probed at dark matter direct detection experiments, and new experimental techniques involving detection of dark matter-electron scattering offer new sensitivity to sub-GeV dark matter. Typically however it is implicitly assumed that the dark matter is not altered as it traverses the Earth to arrive at the detector. In this paper we study in detail the effects of terrestrial stopping on dark photon models of dark matter, and find that they significantly reduce the sensitivity of XENON10 and DAMIC. In particular we find that XENON10 only excludes masses in the range (5-3000) MeV while DAMIC only probes (20-50) MeV. Their corresponding cross section sensitivity is reduced to a window of cross sections between $(5\times 10^{-38}-10^{-30})~{\rm cm}^{2}$ for XENON10 and a small window around $\sim 10^{-31}~{\rm cm}^{2}$ for DAMIC. We also examine implications for a future DAMIC run.