Daily Modulation as a Smoking Gun of Dark Matter with Significant Stopping

TL;DR

This paper explores how dark matter interactions with Earth can cause daily modulation signals in detectors, especially for low-mass dark matter, highlighting a new detection strategy for certain parameter ranges.

Contribution

It introduces the concept of daily modulation caused by Earth stopping dark matter flux, proposing a new detection method for low-mass dark matter with moderate interaction strength.

Findings

Significant Earth stopping can obscure dark matter detection for masses above a few GeV.

Daily modulation signals can arise for dark matter with moderate stopping power.

Surface or shallow detectors in the southern hemisphere can effectively detect these modulated signals.

Abstract

We point out that for a range of parameters, the flux of DM may be stopped significantly by its interactions with the Earth. This can significantly degrade the sensitivity of direct detection experiments to DM candidates with large interactions with terrestrial nuclei. We find that a significant region of parameter space remains unconstrained for DM $\lesssim $ a few GeV. For DM candidates with moderate levels of stopping power, the flux of DM may be blocked from below but not above a detector thereby producing a novel daily modulation. This can be explored by low threshold detectors placed on the surface or in shallow sites in the south hemisphere.