Speaker
Description
Type-II seesaw model, a well motivated new physics scenario to address the origin of neutrino mass issues, includes an extra $SU(2)_L$ complex triplet scalar along with the SM particles. We show that this model can easily accommodate an absolutely stable vacuum until the Planck scale, however with strong limit on the exotic scalar masses and the corresponding mixing angle. We examine the model prediction at the current and future high luminosity run of the Large Hadron Collider (LHC) for the scalar masses and mixing angles fixed at such high-scale valid region. Specifically, we device the associated and pair production of the charged scalars as a new probe of the model at the LHC. We show that for a particular signal process the model can be tested with 5σ signal significance even at the present run of the LHC.
From some special angles, however, a single triplet is inadequate for consistent neutrino mass generation in the Type-II seesaw model. For example, the somewhat different mass and mixing patterns in the neutrino sector (as compared to those in the quark sector) calls for studies in neutrino mass matrix models. One class of such models consists of zero textures, having some vanishing entries in the mass matrix, thus leading to relations between mass eigenvalues and mixing angles, and ensuring better predictiveness in the neutrino sector. It has been shown, that zero textures are inconsistent with Type-II seesaw models. However, the extension of the standard model (SM) with two complex $SU(2)_L$ scalar triplets enables one to have the Type II seesaw mechanism operative consistently with texture-zero neutrino mass matrices. This framework predicts additional doubly charged, singly charged and neutral spinless states. We show that, for certain values of the model parameters, there is sufficient mass splitting between the two doubly charged states($H_1^{\pm\pm}$, $H_2^{\pm\pm}$) that allows the decay $H_1^{\pm\pm} \rightarrow H_2^{\pm\pm} h$, and thus leads to a unique signature of this scenario. We show that the final state $2\ell^{\pm} \ell^{\pm} +4b+{E}_T$ arising from this mode can be observed at the high energy, high luminosity (HE-HL) run of the 14 TeV Large Hadron Collider (LHC).
