Searching for heavy millicharged particles from the atmosphere

TL;DR

This paper investigates the production of millicharged particles in Earth's atmosphere from cosmic ray interactions, analyzing their detection prospects at neutrino experiments like SuperK and JUNO, and extends previous models to include additional production mechanisms.

Contribution

It introduces new production channels for millicharged particles, such as Upsilon decays and Drell-Yan processes, and evaluates their detectability at neutrino detectors.

Findings

JUNO can detect MCPs with charges an order of magnitude higher than current limits for 2-10 GeV masses.

Heavy meson decays and Drell-Yan are dominant sources for MCPs above 1 GeV.

SuperK and JUNO have complementary sensitivities to different MCP mass ranges.

Abstract

If millicharged particles (MCPs) exist they can be created in the atmosphere when high energy cosmic rays collide with nuclei and could subsequently be detected at neutrino experiments. We extend previous work, which considered MCPs from decays of light mesons and proton bremsstrahlung, by including production from $\Upsilon$ meson decays and the Drell-Yan process. MCPs with masses below a GeV primarily arise from proton bremsstrahlung, while heavier MCPs predominantly originate from heavy meson decays and Drell-Yan. We analyse the resulting single scatter and multiple scatter signals at SuperK and JUNO. Searches for low energy coincident signals at JUNO will be sensitive to MCPs with milli-charges up to an order of magnitude beyond current constraints for MCP masses between 2 GeV and 10 GeV.