  The inverse seesaw mechanism allows the neutrino masses to be generated by
new physics at an experimentally accessible scale, even with O(1) Yukawa
couplings. In the inverse seesaw scenario, the smallness of neutrino masses is
linked to the smallness of a lepton number violating parameter. This parameter
may arise radiatively. In this paper, we study the cosmological implications of
two contrasting radiative inverse seesaw models, one due to Ma and the other to
Law and McDonald. The former features spontaneous, the latter explicit lepton
number violation. First, we examine the effect of the lepton-number violating
interactions introduced in these models on the baryon asymmetry of the
universe. We investigate under what conditions a pre-existing baryon asymmetry
does not get washed out. While both models allow a baryon asymmetry to survive
only once the temperature has dropped below the mass of their heaviest fields,
the Ma model can create the baryon asymmetry through resonant leptogenesis.
Then we investigate the viability of the dark matter candidates arising within
these models, and explore the prospects for direct detection. We find that the
Law/McDonald model allows a simple dark matter scenario similar to the Higgs
portal, while in the Ma model the simplest cold dark matter scenario would tend
to overclose the universe.
