Sub-GeV dark matter from cosmic ray bremsstrahlung in the atmosphere

TL;DR

This paper investigates how cosmic ray interactions in the atmosphere can produce boosted sub-GeV dark matter detectable by neutrino observatories and direct detection experiments, extending previous models to higher masses.

Contribution

It models proton bremsstrahlung production of dark matter via initial state radiation, enhancing sensitivity estimates for higher mass ranges and specific mediator resonances.

Findings

Enhanced sensitivity for vector-mediated dark matter near $ ho/\omega$ resonances.

Comparison of detection capabilities between LZ, PandaX-4T, Borexino, and Super-K.

Extended models to higher mass regimes using initial state radiation.

Abstract

We explore the sensitivity of neutrino observatories and direct dark matter detection experiments to boosted sub-GeV dark matter produced by inelastic cosmic ray collisions in the atmosphere. We revisit earlier approaches and extend the sensitivity to higher mass by modeling the proton bremsstrahlung production mode via initial state radiation. For vector-mediated dark matter models, the peak of the cosmic ray flux allows for enhanced DM production for mediator masses near the $\rho/\omega$ resonances. We determine and compare the ensuing sensitivity of direct detection experiments LZ and PandaX-4T and the neutrino detectors Borexino and Super-K.