Higgs boson decay into 2 photons in the type II Seesaw model

A bstract We study the two photon decay channel of the Standard Model-like component of the CP-even Higgs bosons present in the type II Seesaw Model. The corresponding cross-section is found to be significantly enhanced in parts of the parameter space, due to the (doubly-)charged Higgs bosons’ ( H ±± ) H ± virtual contributions, while all the other Higgs decay channels remain Standard Model(SM)-like. In other parts of the parameter space H ±± (and H ± ) interfere destructively, reducing the two photon branching ratio tremendously below the SM prediction. Such properties allow to account for any excess such as the one reported by ATLAS/CMS at ≈ 125 GeV if confirmed by future data; if not, for the fact that a SM-like Higgs exclusion in the diphoton channel around 114-115 GeV as reported by ATLAS, does not contradict a SM-like Higgs at LEP(!), and at any rate, for the fact that ATLAS/CMS exclusion limits put stringent lower bounds on the H ±± mass, particularly in the parameter space regions where the direct limits from same-sign leptonic decays of H ±± do not apply.