  The non-detection of GeV-scale WIMPs has led to increased interest in more
general candidates, including sub-GeV dark matter. Direct detection
experiments, despite their high sensitivity to WIMPs, are largely blind to
sub-GeV dark matter. Recent work has shown that cosmic-ray elastic scattering
with sub-GeV dark matter would both alter the observed cosmic ray spectra and
produce a flux of relativistic dark matter, which would be detectable with
traditional dark matter experiments as well as larger, higher-threshold
detectors for neutrinos. Using data, detectors, and analysis techniques not
previously considered, we substantially increase the regions of parameter space
excluded by neutrino experiments for both dark matter-nucleon and dark
matter-electron elastic scattering. We also show how to further improve
sensitivity to light dark matter.
