Study of two-loop neutrino mass generation models

Abstract

We study the models with the Majorana neutrino masses generated radiatively by two-loop diagrams due to the Yukawa ρℓ̄RcℓR and effective ρ±±W∓W∓ couplings along with a scalar triplet Δ, where ρ is a doubly charged singlet scalar, ℓR the charged lepton and W the charged gauge boson. A generic feature in these types of models is that the neutrino mass spectrum has to be a normal hierarchy. Furthermore, by using the neutrino oscillation data and comparing with the global fitting result in the literature, we find a unique neutrino mass matrix and predict the Dirac and two Majorana CP phases to be 1.41π, 1.11π and 1.48π, respectively. We also discuss the model parameters constrained by the lepton flavor violating processes and electroweak oblique parameters. In addition, we show that the rate of the neutrinoless double beta decay (0νββ) can be as large as the current experimental bound as it is dominated by the short-range contribution at tree level, whereas the traditional long-range one is negligible.