Interpretation of XENON1T excess with MeV boosted dark matter
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, $ S_A $ and $ S_B $ , to interpret the XENON1T keV excess via boosted $ S_B $ . A small mass splitting $ m_{S_A}-m_{S_B}\gt{0} $ is introduced, and the boosted $ S_B $ can be produced using the dark annihilation process of $ S_A S_A^\dagger \to \phi \to S_B S_B^\dagger $ via a resonant scalar ϕ. $ S_B- $ 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 $ X- $ mediated $ S_B- $ electron scattering cross section to be $ \lesssim 10^{-35} \mathrm{cm}^2 $ , the MeV scale DM with a resonance enhanced dark annihilation today can still provide sufficient boosted $ S_B $ and induce the XENON1T keV excess. The relic density of $ S_B $ is significantly reduced by the s-wave process $ S_B S_B^\dagger \to X X $ , which is permitted by the constraints from CMB and 21-cm absorption. A very small relic fraction of $ S_B $ is compatible with the stringent bounds on un-boosted $ S_B $ -electron scattering in DM direct detection, and the $ S_A $ -electron scattering is also allowed. *The work of T. Li was supported by the National Natural Science Foundation of China (11975129, 12035008) and "the Fundamental Research Funds for the Central Universities", Nankai University (63196013). L.-B. Jia acknowledges support from the Longshan academic talent research supporting program of SWUST (18LZX415)
- Publication:
-
Chinese Physics C
- Pub Date:
- August 2022
- DOI:
- 10.1088/1674-1137/ac6d51
- arXiv:
- arXiv:2012.07209
- Bibcode:
- 2022ChPhC..46h3111J
- Keywords:
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- boosted dark matter;
- XENON1T excess;
- dark matter direct detection;
- High Energy Physics - Phenomenology;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 6 pages, 4 figures, the version accepted by CPC