Boosted dark matter from semi-annihilations in the galactic center

In some scenarios, the dark matter relic abundance is set by the semi-annihilation of two dark matter particles into one dark matter particle and one Standard Model particle. These semi-annihilations might still be occurring today in the galactic center at a significant rate, generating a flux of boosted dark matter particles. We investigate the possible signals of this flux component in direct detection and neutrino experiments for sub-GeV dark matter masses. We show that for typical values of the semi-annihilation cross-section, the sensitivity of current experiments to the spin-independent dark matter-proton scattering cross-section can be several orders of magnitude larger than current constraints from cosmic-ray boosted dark matter. We also argue that the upcoming DARWIN and DUNE experiments may probe scattering cross-sections as low as 10 − 37 cm 2 for masses between 30 MeV and 1 GeV. • Semi-annihilation processes in the galaxy can generate a sizeable flux of boosted dark matter. • Direct detection and neutrino experiments can probe sub-GeV dark matter from semi-annihilations. • XENONnT and CRESST-II set strong limits on dark matter-proton scattering for typical semi-annihilation cross-sections. • Upcoming experiments like DARWIN and DUNE could reach sensitivities down to 10 − 37 cm 2 .