Revisiting the Fermionic Dark Matter Absorption on Electron Target

Understand

We perform a systematic study of the fermionic DM absorption interactions on electron target in the context of effective field theory.

• The fermionic DM absorption is not just sensitive to sub-MeV DM with efficient energy release, but also gives a unique signature with clear peak in the electron recoil spectrum whose shape is largely determined by the atomic effects.
• Fitting with the Xenon1T and PandaX-II data prefers DM mass at $m_\chi = 59$keV and 105keV, respectively, while the cut-off scale is probed up to around 1TeV.
• The DM overproduction in the early Universe, the invisible decay effect on the cosmological evolution, and the astrophysical X(gamma)-ray from the DM visible decays are thoroughly explored to give up-to-date constraints.