Scattering meets absorption in dark matter detection

TL;DR

This paper explores how light mediators in dark matter models can be detected through both scattering and absorption in direct detection experiments, highlighting the potential for simultaneous observation and model discrimination.

Contribution

It analyzes the interplay of dark matter scattering and mediator absorption for models with a dark photon, identifying viable parameter space and experimental signatures.

Findings

Scattering and absorption can be simultaneously observed in future experiments.

Additional signals from dark atom scattering are predicted.

Parameter space consistent with cosmological and astrophysical bounds is identified.

Abstract

Direct detection experiments have started to explore dark matter scattering off electrons and nucleons through light mediators. Mediators with sub-keV masses are efficiently produced in the Sun and can be absorbed in the same detectors that probe dark matter scattering. We investigate the interplay of dark matter scattering and mediator absorption for two models with a dark photon as mediator. For Dirac dark matter, we find that scattering and absorption can be simultaneously observed at direct detection experiments in the near future. For atomic dark matter, we predict additional signals due to scattering of both dark atoms and constituents from ionized dark atoms. In both models, we determine the parameter space that respects bounds from cosmology and astrophysics, where the strongest constraints come from dark matter self-interactions. In this way, we identify viable targets for dark matter with light mediators at upcoming direct detection experiments. Distinguishing between the various signals, for instance by measuring energy distributions, will be crucial to reveal the underlying model in case of a discovery.