# Light Dark Matter from Inelastic Cosmic Ray Collisions

## TL;DR

This paper explores a new mechanism for detecting sub-GeV dark matter via inelastic cosmic ray collisions, which produce a high-energy dark matter flux that enhances detection sensitivity in direct detection experiments.

## Contribution

It introduces a novel cosmic beam dump model for dark matter production from inelastic cosmic ray collisions, providing new constraints on light dark matter models.

## Key findings

- Dark matter flux from inelastic cosmic ray collisions can surpass elastic collision flux.
- Limits on hadrophilic scalar mediators are competitive with existing experiments.
- The proposed mechanism extends detection sensitivity to sub-GeV dark matter.

## Abstract

Direct detection experiments relying on nuclear recoil signatures lose sensitivity to sub-GeV dark matter for typical galactic velocities. This sensitivity is recovered if there exists another source of flux with higher momenta. Such an energetic flux of light dark matter could originate from the decay of mesons produced in inelastic cosmic ray collisions. We compute this novel production mechanism---a cosmic beam dump experiment---and estimate the resulting limits from XENON1T and LZ. We find that the dark matter flux from inelastic cosmic rays colliding with atmospheric nuclei can dominate over the flux from elastic collisions with relic dark matter. The limits that we obtain for hadrophilic scalar mediator models are competitive with those from MiniBoone for light MeV-scale mediator masses.