Neutrino mass and dark matter from gaugedU(1)B−Lbreaking

Abstract

We propose a new model where the Dirac mass term for neutrinos, the Majorana mass term for right-handed neutrinos, and the other new fermion masses arise via the spontaneous breakdown of the $\mathrm{U}(1{)}_{\mathrm{B}\ensuremath{-}\mathrm{L}}$ gauge symmetry. The anomaly-free condition gives four sets of assignment of the $\mathrm{B}\ensuremath{-}\mathrm{L}$ charge to new particles, and three of these sets have an associated global $\mathrm{U}(1{)}_{\mathrm{DM}}$ symmetry which stabilizes dark matter candidates. The dark matter candidates contribute to generating the Dirac mass term for neutrinos at the one-loop level. Consequently, tiny neutrino masses are generated at the two-loop level via a type-I-seesaw-like mechanism. We show that this model can satisfy current bounds from neutrino oscillation data, the lepton flavor violation, the relic abundance of the dark matter, and the direct search for the dark matter. This model would be tested at future collider experiments and dark matter experiments.