(In)direct Detection of Boosted Dark Matter

TL;DR

This paper explores a new detection method for boosted dark matter particles produced by galactic annihilation, which can be observed via terrestrial experiments sensitive to electron or nuclear interactions, especially in multi-component dark sector models.

Contribution

It introduces the concept of detecting boosted dark matter from galactic annihilation in non-minimal dark sectors, demonstrating a specific two-component model with detectable signals in neutrino and proton decay experiments.

Findings

Boosted dark matter can produce detectable electron scattering signals.

Detection is promising for dark sector masses between 10 MeV and 10 GeV.

Experiments like Super-K, Hyper-K, and IceCube extensions are suitable for observation.

Abstract

We initiate the study of novel thermal dark matter (DM) scenarios where present-day annihilation of DM in the galactic center produces boosted stable particles in the dark sector. These stable particles are typically a subdominant DM component, but because they are produced with a large Lorentz boost in this process, they can be detected in large volume terrestrial experiments via neutral-current-like interactions with electrons or nuclei. This novel DM signal thus combines the production mechanism associated with indirect detection experiments (i.e. galactic DM annihilation) with the detection mechanism associated with direct detection experiments (i.e. DM scattering off terrestrial targets). Such processes are generically present in multi-component DM scenarios or those with non-minimal DM stabilization symmetries. As a proof of concept, we present a model of two-component thermal relic DM, where the dominant heavy DM species has no tree-level interactions with the standard model and thus largely evades direct and indirect DM bounds. Instead, its thermal relic abundance is set by annihilation into a subdominant lighter DM species, and the latter can be detected in the boosted channel via the same annihilation process occurring today. Especially for dark sector masses in the 10 MeV-10 GeV range, the most promising signals are electron scattering events pointing toward the galactic center. These can be detected in experiments designed for neutrino physics or proton decay, in particular Super-K and its upgrade Hyper-K, as well as the PINGU/MICA extensions of IceCube. This boosted DM phenomenon highlights the distinctive signatures possible from non-minimal dark sectors.