ν-Two Higgs doublet model and its collider phenomenology

Smallness of neutrino masses can be explained by introducing a tiny vacuum expectation value of an extra-Higgs doublet which couples to right-handed neutrinos (NR). This situation is naturally realized in ν-Two Higgs Doublet Model (νTHDM), where a TeV-scale seesaw mechanism can work well. We investigate observable phenomenology of νTHDM at LHC and ILC experiments. Charged Higgs boson (H^±) in νTHDM is almost originated from the extra-Higgs doublet and its coupling strength to neutrinos are not small. Then this model induces rich phenomenology at the LHC, for example, when m _H^± > MN, observable charged tracks can be induced from long lived charged Higgs. On the other hand, when mH ^± < MN, right-handed neutrinos can be long-lived, and secondary vertices may be tagged at the LHC. The νTHDM also predicts observable lepton number violating process at the ILC.