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

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 O(MeV) mass, far beyond what can be obtained with nuclear recoils alone.

Automated summary

The study examines inelastic scattering of low-mass dark matter using the Migdal effect at direct detection experiments, revealing degeneracies between dark matter mass and mass splitting that are challenging to overcome. Utilizing XENON1T data, constraints are placed on an unexplored region of the inelastic dark matter parameter space. For exothermic scattering, the Migdal effect enables xenon-based detectors to detect dark matter with O(MeV) mass, surpassing the sensitivity achievable with nuclear recoils alone.