https://doi.org/10.1140/epjc/s10052-018-6439-z
Letter
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
* e-mail: jialb@mail.nankai.edu.cn
Received:
12
September
2018
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
