Gauged $U(1)_X$ breaking as origin of neutrino masses, dark matter and leptogenesis at TeV scale

Abstract: We propose a new mechanism which simultaneously explains tiny neutrino masses, stability of dark matter and baryon asymmetry of the Universe via leptogenesis due to the common origin: a spontaneous breaking of a $U(1)_X$ gauge symmetry at TeV scale. The $U(1)_X$ breaking provides small Majorana masses of vector-like leptons which generate small mass differences among them, and enhance their CP-violating decays via the resonant effect. Such CP-violation and lepton number violation turns out to be a sufficient amount of the observed baryon asymmetry through leptogenesis. The Majorana masses from the $U(1)_X$ breaking also induce radiative generation of masses for active neutrinos at one-loop level. Furthermore, a $Z_2$ symmetry appears as a remnant of the $U(1)_X$ breaking, which guarantees the stability of dark matter. We construct a simple renormalizable model to realize the above mechanism, and show a benchmark point which can explain observed neutrino oscillations, dark matter data and the baryon asymmetry at the same time.