The Direct Detection of Boosted Dark Matter at High Energies and PeV events at IceCube

Abstract: We study the possibility of detecting dark matter directly via a small but energetic component that is allowed within present-day constraints. Drawing closely upon the fact that neutral current neutrino nucleon interactions are indistinguishable from DM-nucleon interactions at low energies, we extend this feature to high energies for a small, non-thermal but highly energetic population of DM particle $\chi$, created via the decay of a significantly more massive and long-lived non-thermal relic $\phi$, which forms the bulk of DM. If $\chi$ interacts with nucleons, its cross-section, like the neutrino-nucleus coherent cross-section, can rise sharply with energy leading to deep inelastic scattering, similar to neutral current neutrino-nucleon interactions at high energies. Thus, its direct detection may be possible via cascades in very large neutrino detectors. As a specific example, we apply this notion to the recently reported three ultra-high energy PeV cascade events clustered around $1-2$ PeV at IceCube (IC). We discuss the features which may help discriminate this scenario from one in which only astrophysical neutrinos constitute the event sample in detectors like IC.