Lepton flavor violation in the triplet Higgs model

The triplet Higgs model, which is an extension of the standard model with a weak-scale triplet Higgs boson, is capable of generating small neutrino masses naturally. We investigate lepton flavor violation mediated by the triplet Higgs boson. We stress that various neutrino mass patterns could be distinguished by measuring the lepton flavor violating processes. μ → eee decay is significantly enhanced in the case of the degenerate masses or the inverted-hierarchical masses compared with that in the case of the hierarchical masses. On the other hand, the μ → eγ rate and the μ-e conversion ratio in nuclei is almost insensitive to the mass spectra. We also emphasize that these decay rates tend to increase as the magnitude of U_e3 increases. Lepton flavor nonconserving τ decay modes are expected to be unobservable at planned experiments in the light of the current upper bounds of flavor violating muonic decay.