We study cosmic-ray-atmosphere collisions as a permanent production source of exotic millicharged particles (MCPs) for all terrestrial experiments. [MCPs are also known as charged massive particles (CHAMPs).] Based on data from Super-K, this allows us to derive new limits on MCPs that are competitive with, or improve, the currently leading bounds from accelerator-based searches for masses up to 1.5 GeV. In models where a subdominant component of dark matter (DM) is fractionally charged, these constraints probe parts of the parameter space that is inaccessible for conventional direct-detection DM experiments, independently of assumptions about the DM abundance.
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We would like to thank Dr. T.-T. Yu for a stimulating discussion of the cosmic-ray-generated light dark matter flux. We also thank Professor M. Kachelrieß, Dr. M. Smy and Professor H. Sobel for discussions. We thank Roni Harnik and Zhen Liu for providing us with the ArgoNeuT exclusion curves directly. R. P. and Y. -D. T. thank the University of Washington and the Institute for Nuclear theory for its hospitality during the final portion of this work. R. P. also thanks the Fermilab theory group for their hospitality and support. Y. -D. T. would like to thank Kavli Institute of Cosmological Physics (KICP), University of Chicago, for the hospitality and support. The work of A. K. and V. T. was supported by the U.S. Department of Energy (DOE) Grant No. DE-SC0009937. The work of A. K. was also supported by the World Premier International Research Center Initiative, MEXT Japan. The work of R. P. was supported by an the Government of Canada through an NSERC PGS-D award and by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under Award No. DE-SC0019095. This paper has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. This work was partly performed at the Aspen Center for Physics, which is supported by National Science Foundation Grant No. PHY-1607611. Research at the Perimeter Institute was supported in part by the Government of Canada through NSERC and by the Province of Ontario through Ministry of Economic Development, Job Creation and Trade (MEDT).
© 2020 authors. Published by the American Physical Society.