Two-Higgs-Doublet Type-II Seesaw Model

Motivated by the new observed scalar boson of 126 GeV at ATLAS and CMS, various phenomena in two-Higgs-doublet model (THDM) 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 triplet and doublet. As a result, we have a completely different decay pattern for doubly charged Higgs ($\delta^{\pm\pm}$), even the vacuum expectation value (VEV) of Higgs triplet is at GeV level, which is limited by the precision measurement for $\rho$-parameter. For illustrating the new characters of the model, we study the influence of new interactions on the new open channels $\delta^{++}\to ( H^+_1 W^{+^{(*)}}, H^+_1 H^+_1)$ 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 $\delta^{++}$ via $\delta^{++}\to tb W^+ \to b \bar b W^+ W^+$ by mediated $H^+_{1}$ becomes significant.