Direct detection of freeze-in inelastic dark matter

TL;DR

This paper demonstrates that existing direct detection experiments can already probe inelastic freeze-in dark matter models, constraining parameter space and potentially explaining observed electron recoil excesses.

Contribution

It provides the first direct detection constraints on inelastic freeze-in dark matter and links these models to experimental signals and anomalies.

Findings

Current experiments constrain inelastic freeze-in dark matter models.

Models with keV-scale mass gaps can explain electron recoil excess.

Existing data already probe interesting dark matter parameter space.

Abstract

We show that the current sensitivities of direct detection experiments have already reached the interesting parameter space of freeze-in dark matter models if the dark sector is in the inelastic dark matter framework and the excited dark matter state is cosmologically stable. Using results recently presented by the XENON1T experiment, we present constraints on these models. We also show that these models can explain the reported excess in the electron recoil signals if the mass gap between the ground state and the excited state is at keV scale.