Radiative neutrino mass model with a TeV scale gauge symmetry

The radiative neutrino mass model can relate neutrino masses to dark matter at TeV regions. In order for thermal leptogenesis to work well in this model, both nely degenerate mass of the right-handed neutrinos and a tiny neutrino Yukawa coupling are necessary for resonant out-of-equilibrium decay. We show these features could be realized through an extension of the model with a U(1) gauge symmetry. This extension can also bring about a small quartic scalar coupling between the Higgs doublet scalar and an inert doublet scalar, and the origin of the Z2 symmetry which guarantees the stability of dark matter.