Xenon1T excess from electron recoils of non-relativistic Dark Matter
We show that electron recoils induced by non-relativistic Dark Matter interactions can fit well the recently reported Xenon1T excess, if they are mediated by a light pseudo-scalar in the MeV range. This is due to the favorable momentum-dependence of the resulting scattering rate, which partially compensates the unfavorable kinematics that tends to strongly suppress keV electron recoils. We study the phenomenology of the mediator and identify the allowed parameter space of the Xenon1T excess which is compatible with all experimental limits. We also find that the anomalous magnetic moments $(g-2)_{\mu,e}$ of muons and electrons can be simultaneously explained in this scenario, at the prize of a fine-tuning in the couplings of the order of a few percent.