We study the most popular nonminimal Higgs extension of the Standard Model, namely the two-Higgs-doublet model, extended by a complex triplet scalar (2HDMcT). Such model with a very small vacuum expectation value, provides a solution to the massive neutrinos through the so-called type-II seesaw mechanism. We show that the 2HDMcT enlarged parameter space allow for a rich and interesting phenomenology compatible with current experimental constraints. In this paper the 2HDMcT is subject to a detailed scrutiny. Indeed, a complete set of tree level unitarity constraints on the coupling parameters of the potential is determined, and the exact tree-level boundedness from below constraints on these couplings are generated for all directions. Moreover, we also include in our study: electroweak precision test constraints, LEP and recents LHC constraints as well as some selected set of lepton flavor violation constraints. We then perform an extensive parameter scan in the 2HDMcT parameter space, delimited by the above derived theoretical constraints as well as by experimental limits. We find that an important triplet admixtures are still compatible with the Higgs data and investigate which observables will allow us to restrict the triplet nature most effectively in the next runs of the LHC. Finally, we emphasize new production and decay channels and their phenomenological relevance and treatment at the LHC.

• Received 17 February 2019

DOI:https://doi.org/10.1103/PhysRevD.100.035031

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

Published by the American Physical Society