Constraints on MeV dark matter using neutrino detectors and their implication for the 21-cm results

TL;DR

This paper investigates constraints on MeV-scale milli-charged dark matter annihilating into neutrinos, using neutrino detector data, and discusses implications for the 21-cm cosmological observations, highlighting potential future experimental bounds.

Contribution

It explores the unconstrained parameter space of milli-charged dark matter annihilating into neutrinos, providing updated limits and future prospects with upcoming neutrino detectors.

Findings

Super-Kamiokande data currently does not constrain this dark matter model.

Future experiments like Hyper-Kamiokande, JUNO, and DUNE could set meaningful limits.

The model involves dark matter making up about 2% of total dark matter, annihilating into mu and tau neutrinos.

Abstract

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.