Lepton flavor violating Higgs boson decays in seesaw models: New discussions

The lepton flavor violating decay of the Standard Model-like Higgs boson (LFVHD), h→μτ, is discussed in seesaw models at the one-loop level. Based on particular analytic expressions of Passarino-Veltman functions, the two unitary and 't Hooft Feynman gauges are used to compute the branching ratio of LFVHD and compare with results reported recently. In the minimal seesaw (MSS) model, the branching ratio was investigated in the whole valid range 10−9-1015 GeV of new neutrino mass scale mn6. Using the Casas-Ibarra parameterization, this branching ratio enhances with large and increasing mn6. But the maximal value can reach only order of 10−11. Interesting relations of LFVHD predicted by the MSS and inverse seesaw (ISS) model are discussed. The ratio between two LFVHD branching ratios predicted by the ISS and MSS is simply mn62μX−2, where μX is the small neutrino mass scale in the ISS. The consistence between different calculations is shown precisely from analytical approach.