Interpretation of XENON1T excess with MeV boosted dark matter |
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| Authors: | Lian-Bao Jia Tong Li |
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| Affiliation: | 1. School of Science, Southwest University of Science and Technology, Mianyang 621010, China2. School of Physics, Nankai University, Tianjin 300071, China |
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| Abstract: | The XENON1T excess of keV electron recoil events may be induced by the scattering of electrons and long-lived particles with an MeV mass and high speed. We consider a tangible model composed of two scalar MeV dark matter (DM) particles, begin{document}$ S_A $end{document}![]() ![]() and begin{document}$ S_B $end{document}![]() ![]() , to interpret the XENON1T keV excess via boosted begin{document}$ S_B $end{document}![]() ![]() . A small mass splitting begin{document}$ m_{S_A}-m_{S_B}>0 $end{document}![]() ![]() is introduced, and the boosted begin{document}$ S_B $end{document}![]() ![]() can be produced using the dark annihilation process of begin{document}$ S_A S_A^dagger to phi to S_B S_B^dagger $end{document}![]() ![]() via a resonant scalar ?. begin{document}$ S_B- $end{document}![]() ![]() electron scattering is intermediated by a vector boson X. Although the constraints from Big Bang nucleosynthesis, cosmic microwave background (CMB), and low-energy experiments set the begin{document}$ X- $end{document}![]() ![]() mediated begin{document}$ S_B- $end{document}![]() ![]() electron scattering cross section to be begin{document}$ lesssim 10^{-35} mathrm{cm}^2 $end{document}![]() ![]() , the MeV scale DM with a resonance enhanced dark annihilation today can still provide sufficient boosted begin{document}$ S_B $end{document}![]() ![]() and induce the XENON1T keV excess. The relic density of begin{document}$ S_B $end{document}![]() ![]() is significantly reduced by the s-wave process begin{document}$ S_B S_B^dagger to X X $end{document}![]() ![]() , which is permitted by the constraints from CMB and 21-cm absorption. A very small relic fraction of begin{document}$ S_B $end{document}![]() ![]() is compatible with the stringent bounds on un-boosted begin{document}$ S_B $end{document}![]() ![]() -electron scattering in DM direct detection, and the begin{document}$ S_A $end{document}![]() ![]() -electron scattering is also allowed. |
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| Keywords: | boosted dark matter XENON1T excess dark matter direct detection |
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