(In)direct Detection of Boosted Dark Matter
  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.
