Two-Higgs-doublet type-II seesaw model

Abstract

Motivated by the new observed scalar boson of 126 GeV at ATLAS and CMS, various phenomena in the two-Higgs-doublet model are investigated broadly in the literature. For considering the model that possesses a solution to the massive neutrinos, we study the simplest extension of conventional type-II seesaw model to two Higgs doublets. We find that the new interactions in the scalar potential cause the sizable mixture of charged Higgses in a triplet and doublets. As a result, we have a completely different decay pattern for doubly charged Higgs (${\ensuremath{\delta}}^{\ifmmode\pm\else\textpm\fi{}\ifmmode\pm\else\textpm\fi{}}$); even the vacuum expectation value of a Higgs triplet is at GeV level, which is limited by the precision measurement for the $\ensuremath{\rho}$ parameter. For illustrating the new characters of the model, we study the influence of new interactions on the new open channels ${\ensuremath{\delta}}^{++}\ensuremath{\rightarrow}({H}_{1}^{+}{W}^{{+}^{(*)}},{H}_{1}^{+}{H}_{1}^{+})$ with ${H}_{1}^{+}$ being the lightest charged Higgs. Additionally, due to the new mixing effect, the triplet charged Higgs could couple to quarks in the model; therefore, the search for ${\ensuremath{\delta}}^{++}$ via ${\ensuremath{\delta}}^{++}\ensuremath{\rightarrow}tb{W}^{+}\ensuremath{\rightarrow}b\overline{b}{W}^{+}{W}^{+}$ by mediated ${H}_{1}^{+}$ becomes significant.