Cosmic-ray upscattered inelastic dark matter

TL;DR

This paper demonstrates that cosmic-ray upscattering enables direct detection of inelastic dark matter with larger mass splittings and lower masses than previously possible, expanding the accessible parameter space.

Contribution

It extends the cosmic-ray dark matter formalism to inelastic models, allowing exploration of previously unreachable mass-splitting regions in direct detection experiments.

Findings

Cosmic-ray upscattering probes larger mass splittings (~100 MeV).

Extends detection reach to lower dark matter masses.

Increases sensitivity to inelastic dark matter models.

Abstract

Light non-relativistic components of the galactic dark matter halo elude direct detection constraints because they lack the kinetic energy to create an observable recoil. However, cosmic-rays can upscatter dark matter to significant energies, giving direct detection experiments access to previously unreachable regions of parameter-space at very low dark matter mass. In this work we extend the cosmic-ray dark matter formalism to models of inelastic dark matter and show that previously inaccessible regions of the mass-splitting parameter space can be probed. Conventional direct detection of non-relativistic halo dark matter is limited to mass splittings of $\delta\sim10~\mathrm{keV}$ and is highly mass dependent. We find that including the effect of cosmic-ray upscattering can extend the reach to mass splittings of $\delta\sim100~\mathrm{MeV}$ and maintain that reach at much lower dark matter mass.