Low-mass inelastic dark matter direct detection via the Migdal effect

TL;DR

This paper explores how the Migdal effect can enhance the detection of low-mass inelastic dark matter in direct detection experiments, revealing new parameter space constraints and sensitivity improvements.

Contribution

It demonstrates the potential of the Migdal effect to improve sensitivity to low-mass inelastic dark matter, especially for exothermic scattering, using existing XENON1T data.

Findings

Set bounds on inelastic dark matter using XENON1T data.

Showed Migdal effect extends sensitivity to MeV-scale dark matter.

Identified degeneracies between dark matter mass and mass splitting.

Abstract

We consider searches for the inelastic scattering of low-mass dark matter at direct detection experiments, using the Migdal effect. We find that there are degeneracies between the dark matter mass and the mass splitting that are difficult to break. Using XENON1T data we set bounds on a previously unexplored region of the inelastic dark matter parameter space. For the case of exothermic scattering, we find that the Migdal effect allows xenon-based detectors to have sensitivity to dark matter with ${\cal O}(\mathrm{MeV})$ mass, far beyond what can be obtained with nuclear recoils alone.