Enhancement of the Higgs decay into a Z′ pair in models with U(1) gauge symmetry

We discuss the Higgs phenomenology in models with a new U(1)X gauge symmetry including the U(1)B−L scenario, where three right-handed neutrinos are inevitably introduced due to the gauge anomaly cancellations. We find that the decay branching ratio of the discovered Higgs boson into a pair of new massive gauge bosons (Z′) can significantly be enhanced in the Dirac neutrino case as compared with the Majorana case for a fixed value of the new gauge coupling and the mass of Z′ under constraints from current experimental data. Because of such an enhancement, the Dirac case can indirectly be discriminated from the Majorana case via the Higgs decay.