Constraints on MeV dark matter using neutrino detectors and their
  implication for the 21-cm results
  The recent results of the EDGES collaboration indicate that during the era of
reionization, the primordial gas was much colder than expected. The cooling of
the gas could be explained by interactions between dark matter (DM) and
particles in the primordial gas. Constraints from cosmology and particle
experiments indicate that this DM should be light ($\sim$10-80 MeV), carry a
small charge ($\epsilon\sim 10^{-6}$-$10^{-4}$), and only make up a small
fraction of the total amount of DM. Several constraints on the DM parameter
space have already been made. We explore the yet unconstrained region in the
case that the milli-charged DM makes up for $\sim$2\% of the total dark matter,
through the scenario in which this DM annihilates only into mu and tau
neutrinos. We set upper limits on the annihilation cross section using the
Super-Kamiokande data, and predict the limits that could be obtained through
Hyper-Kamiokande, JUNO and DUNE. We find that data from Super-Kamiokande is not
yet able to constrain this model, but future experiments might be. We
furthermore explore DM annihilation into solely neutrinos in general, giving an
update of the current limits, and predict the limits that could be placed with
future experiments.
