Millicharged Particles from the Heavens: Single- and Multiple-Scattering Signatures

Understand

For nearly a century, studying cosmic-ray air showers has driven progress in our understanding of elementary particle physics.

• In this work, we revisit the production of millicharged particles in these atmospheric showers and provide new constraints for XENON1T and Super-Kamiokande and new sensitivity estimates of current and future detectors, such as JUNO.
• We discuss distinct search strategies, specifically studies of single-energy-deposition events, where one electron in the detector receives a relatively large energy transfer, as well as multiple-scattering events consisting of (at least) two relatively small energy depositions.
• We demonstrate that these atmospheric search strategies -- especially this new, multiple-scattering signature -- provide significant room for improvement in the next decade, in a way that is complementary to anthropogenic, beam-based searches for MeV-GeV millicharged particles.