Diurnal Effect of Sub-Gev Dark Matter Boosted by Cosmic Rays
Diurnal Effect of Sub-GeV Dark Matter Boosted by Cosmic Rays Shao-Feng Ge,1,2, ∗ Jianglai Liu,2,1, † Qiang Yuan,3, 4, 5, ‡ and Ning Zhou2, § 1Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China 2School of Physics and Astronomy, Shanghai Jiao Tong University, Key Laboratory for Particle Astrophysics and Cosmology (MOE) & Shanghai Key Laboratory for Particle Physics and Cosmology, Shanghai 200240, China 3Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210033, China 4School of Astronomy and Space Science, University of Science and Technology of China, Hefei 230026, China 5Center for High Energy Physics, Peking University, Beijing 100871, China We point out a new type of diurnal effect for the cosmic ray boosted dark matter (DM). The DM- nucleon interactions not only allow the direct detection of DM with nuclear recoils, but also allow cosmic rays to scatter with and boost the nonrelativistic DM to higher energies. If the DM-nuclei scattering cross sections are sufficiently large, the DM flux is attenuated as it propagates through the Earth, leading to a strong diurnal modulation. This diurnal modulation provides another prominent signature for the direct detection of boosted sub-GeV DM, in addition to signals with higher recoil energy. Introduction – Overwhelming evidence from astrophys- signals in large neutrino experiments [44–46]. ical and cosmological observations supports the existence For sub-GeV DM, the DM-nucleon scattering cross sec- of dark matter (DM) [1], which is gravitationally interact- tion with a contact interaction can be quite sizable, e.g., ing but invisible via electromagnetic interactions.
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