Scalar phenomenology in type-II seesaw model

Abstract

In this work we study the viable parameter space of the scalar sector in the type-II seesaw model. In identifying the allowed parameter space, we employ constraints from low energy precision measurements, theoretical considerations and the 125-GeV Higgs data. These tools prove effective in constraining the model parameter space. Moreover, the triplet also offers a rich collider phenomenology from having additional scalars that have unique collider signatures. We find that direct collider searches for these scalars can further probe various parts of the viable parameter space. These parts can be parametrized by the electroweak scalar triplet vacuum expectation value, the mass splitting of the singly-and doubly-charged scalars, and the doubly-charged Higgs mass. We find that different regions of the viable parameter space give rise to different collider signatures, such as the same-sign dilepton, the same-sign W and the multilepton signatures. By investigating various LEP and LHC measurements, we derive the most updated constraints over the whole range of parameter space of the type-II seesaw model.

LHC signals of a heavy doublet Higgs as dark matter portal: cut-based approach and improvement with gradient boosting and neural networks

“…So long as there is small mixing between the dark matter particle χ and the scalar triplet and doublet, which is ensured by the smallness of the triplet VEV as compared to that of the doublet, the main constraints on the scalar sector remain similar as for the Type-II Seesaw model, as discussed in [18]. We summarize them below, and turn to the additional constraints on the dark matter sector.…”

“…The triplet within this model have potential to induce Majorana neutrino masses via interactions with the left-handed lepton doublet L ≡ (ν, l) T [18,26]. The Yukawa terms with (∆L = 2) can be written as…”

“…However, the LHC-related prediction does not change appreciably (beyond 10%) in the normal hierarchy (NH) or inverted hierarchy (IH) scenarios as well. In the degenerate case, using the central values of entries in the PMNS matrix [18], one obtains…”

“…Here we present the results of a similar investigation in the context of scalar triplet extension of the SM [4][5][6][7][8][9][10][11][12][13][14][15][16], together with a scalar DM candidate χ [17]. A Y = 2 scalar triplet added to the SM doublet, with the triplet vacuum expectation value (VEV) limited to < ∼ 4.8 GeV by the ρ-parameter [18], can generate Majorana masses for neutrinos via the Type-II Seesaw mechanism. It also has a rich collider phenomenology [19][20][21][22][23][24], largely due to the presence of a doubly charged scalar that decays either to same-sign dileptons or same-sign W pairs.…”

Lepton flavor violation and collider searches in a type I + II seesaw model

“…There are other important limits on this scenario [83,[95][96][97][98] but the ones we quote are the most relevant. For a more complete discussion of the collider bounds on the type II seesaw we refer to [99].…”