Multi-Higgs doublet models with local U(1)H gauge symmetry and neutrino physics therein

Multi-Higgs doublet models appear in many interesting extensions of the standard model (SM). But they suffer from Higgs-mediated flavor changing neutral current (FCNC) problem which is very generic. In this talk, I describe that this problem can be resolved or mitigated if we introduce local U(1)H Higgs flavor gauge symmetry. As examples, I describe chiral U(1)H models where the right-handed up-type quarks also carry U(1)H charges and discuss the top forward-backward asymmetry (FBA) and B → D(*)τν puzzle. Next I describe the two-Higgs doublet models where the usual Z2 symmetry is implemented to U(1)H and show how the Type-I and Type-II models are extended. One possible extension of Type-II has the same fermion contents with the leptophobic E6Z′ model by Rosner, and I discuss the neutrino sector in this model briefly