Cosmic-ray upscattered inelastic dark matter

Light nonrelativistic 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 p ammeter space can be probed. Conventional direct detection of nonrelativistic halo dark matter is limited to mass splittings of delta similar to 10 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 similar to 100 MeV and maintain that reach at much lower dark matter mass.