Speaker
Description
The Type-II Seesaw provides a mechanism for generating non-zero neutrino masses by extending the scalar sector of the Standard model with a complex triplet. The additional scalar states predicted by the model can be probed indirectly through their contributions to rare processes involving the Higgs boson.
In this talk, we investigate the phenomenological signatures of Type-II Seesaw in the h → γγ and h → Zγ decays, as well as in the associated production of a Higgs boson with a photon in electron-positron scattering. The experimental value of the ρ parameter motivates the vΔ ≪ v limit, in which the dominant Type-II corrections to the considered processes arise from the singly and doubly charged scalar loops. At zeroth order in vΔ/v, the Type-II predictions depend on the mass of the doubly charged scalar, the charged scalar mass splitting, and the bi-quadratic coupling λhΔ1.
We discuss the constraints on the Type-II parameter space given by the experimental measurements of the h → γγ and h → Zγ signal strengths. We explore the sensitivity of the e+e− → hγ unpolarized scattering cross section to Type-II corrections. Assuming 10% deviations from the Standard model prediction might be experimentally
accessible, the process could probe regions of the parameter space with negative mass splittings and, in particular, negative bi-quadratic coupling, which are comparatively weakly constrained by the two Higgs decays.