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

TL;DR

This paper explores the production and detection of millicharged particles from cosmic-ray air showers, proposing new search strategies and providing updated constraints and sensitivity estimates for various detectors, including a Monte Carlo simulation framework.

Contribution

It introduces novel atmospheric search strategies, especially multiple-scattering signatures, and offers new constraints and sensitivity estimates for millicharged particles in large-volume detectors.

Findings

Significant potential for improved detection in the next decade.

New constraints on millicharged particles from XENON1T and Super-Kamiokande.

Development of a Monte Carlo simulation for large-volume neutrino detectors.

Abstract

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. Finally, we also discuss the implementation of a Monte Carlo simulation for millicharged particle detection in large-volume neutrino detectors, such as IceCube.