Daily modulation and gravitational focusing in direct dark matter search experiments

TL;DR

This paper investigates how Earth's gravitational focusing can cause detectable daily modulations in dark matter detection signals, offering a new way to verify or falsify dark matter hypotheses in experiments.

Contribution

It introduces the concept that gravitational focusing induces a distinguishable diurnal modulation, providing a novel method to test the consistency of dark matter detection signals.

Findings

Gravitational focusing can produce detectable daily modulation in dark matter signals.

Diurnal modulation phases differ from Earth's rotation effects, allowing distinction.

Null results can be used to check for background modulations, potentially revealing vetoed dark matter events.

Abstract

We study the effect of gravitational focusing of the earth on dark matter. We find that the effect can produce a detectable diurnal modulation in the dark matter signal for part of the parameter space which for high dark matter masses is larger than the diurnal modulation induced by the fluctuations in the flux of dark matter particles due to the rotation of the earth around its own axis. The two sources of diurnal modulation have different phases and can be distinguished from each other. We demonstrate that the diurnal modulation can potentially check the self-consistency of experiments that observe annual modulated signals that can be attributed to dark matter. Failing to discover a daily varying signal can result conclusively to the falsification of the hypothesis that the annual modulation is due to dark matter. We also suggest that null result experiments should check for a daily modulation of their rejected background signal with specific phases. A potential discovery could mean that dark matter collisions have been vetoed out.