Present and future status of light dark matter models from cosmic-ray
  electron upscattering
  Non-relativistic Dark Matter (DM) can be accelerated by scattering on
high-energy cosmic-ray (CR) electrons. This process leads to a sub-population
of relativistic or semi-relativistic DM which extends the experimental reach
for direct detection in the sub-GeV mass regime. In this paper we examine the
current and future potential of this mechanism for constraining models of light
dark matter. In particular, we find that Super-Kamiokande and XENON1T data can
already provide leading constraints on the flux of dark matter that has been
accelerated to high energies from cosmic ray electrons. We also examine future
projected sensitivities for DUNE and Hyper-K, and contrary to previous
findings, conclude that DUNE will be able supersede Super-K bounds on
cosmic-ray upscattered DM for a variety of DM models.
