Could the 21-cm absorption be explained by the dark matter suggested by Be transitions?
School of Science, Southwest University of Science and Technology, Mianyang, 621010, China
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Accepted: 10 November 2018
Published online: 21 November 2018
The stronger than expected 21-cm absorption was observed by EDGES recently, and another anomaly of Be transitions would be signatures of new interactions. These two issues may be related to each other, e.g., pseudoscalar A mediated fermionic millicharged dark matter (DM) and the 21-cm absorption could be induced by photon mediated scattering between MeV millicharged DM and hydrogen. This will be explored in this paper. For fermionic millicharged DM with masses in a range of , the p-wave annihilation would be dominant during DM freeze-out. The s-wave annihilation is tolerant by constraints from CMB and the 21-cm absorption. The millicharged DM can evade constraints from direct detection experiments. The process of with the invisible decay could be employed to search for the millicharged DM, and future high intensity sources, such as NA62, will do the job.
© The Author(s), 2018