Flavor dependent U(1) symmetric Zee model with a vector-like lepton

Abstract

We extend the Zee model by introducing a vector-like lepton doublet and a flavor dependent global U(1) symmetry. Flavor changing neutral currents in the quark sector can be naturally forbidden at tree level due to the U(1) symmetry, while sufficient amount of lepton flavor violation is provided to explain current neutrino oscillation data. In our model, additional sources of CP-violation appear in the lepton sector, but their contribution to electric dipole moments is much smaller than current experimental bounds due to the Yukawa structure constrained by the U(1) symmetry. We find that there is a parameter region where the strongly first order electroweak phase transition can be realized, which is necessary for the successful scenario of the electroweak baryogenesis in addition to new CP-violating phases. In the benchmark points satisfying neutrino data, lepton flavor violation data and the strongly first order phase transition, we show that an additional CP-even Higgs boson H mainly decays into a lighter CP-odd Higgs boson A, i.e., H -> AZ or H -> AA with a characteristic pattern of lepton flavor violating decays of A. (C) 2021 The Author(s). Published by Elsevier B.V.