  The generation of lepton asymmetry below the electroweak scale has a
considerable impact on production of dark matter sterile neutrinos.
Oscillations or decays of the heavier sterile neutrinos in the neutrino minimal
standard model can give rise to the requisite lepton asymmetry, provided the
masses of the heavier neutrinos are sufficiently degenerate. We study the
renormalization group evolution of the mass difference of these singlet
fermions to understand the degree of necessary fine-tuning. We construct an
example of the model that can lead to a technically natural realization of this
low-energy degeneracy.
