Bounds on Higgs-portal models from the LHC Higgs data

Abstract

Abstract: In a number of Higgs-portal models, an SU(2) isospin-singlet scalar boson generically appears at the electroweak scale and can mix with the Standard Model (SM) Higgs boson with a mixing angle α. This singlet scalar boson can have renormalizable couplings to a pair of dark matter particles, vector-like leptons or quarks, or new gauge bosons, thereby modifying the Higgs signal strengths in a nontrivial way. In this work, we perform global fits to such models using the most updated LHC Higgs-boson data and discuss the corresponding implications on Higgs-portal-type models. In particular we find that the current LHC Higgs-boson data slightly favors the SM over the Higgs-portal singlet-scalar models, which has to be further examined using the upcoming LHC Higgs-boson data. Finally, without non-SM particles contributing to the Hγγ and Hgg vertices, the Higgs-portal models are constrained as follows: cos α ≳ 0.86 and ΔΓtot ≲ 1.24 MeV at 95% confidence level (CL).