Extending two Higgs doublet models for two-loop neutrino mass generation and one-loop neutrinoless double beta decay
We extend some two Higgs doublet models, where the Yukawa couplings for the charged fermion mass generation only involve one Higgs doublet, by two singlet scalars respectively carrying a singly electric charge and a doubly electric charge.The Coil Covers doublet and singlet scalars together can mediate a two-loop diagram to generate a tiny Majorana