Possible Capture of keV Sterile Neutrino Dark Matter on Radioactive beta-decaying Nuclei

Understand

There exists an observed "desert" spanning six orders of magnitude between O(0.5) eV and O(0.5) MeV in the fermion mass spectrum.

• We argue that it might accommodate one or more keV sterile neutrinos as a natural candidate for warm dark matter.
• To illustrate this point of view, we simply assume that there is one keV sterile neutrino nu_4 and its flavor eigenstate nu_s weakly mixes with three active neutrinos.
• We clarify different active-sterile neutrino mixing factors for the radiative decay of nu_4 and beta decays in a self-consistent parametrization.