Higgs couplings in a model with triplets

TL;DR

This paper explores how the presence of triplet scalars in a Higgs model can enhance Higgs couplings to W and Z bosons, leading to observable deviations from Standard Model predictions at colliders.

Contribution

It introduces a Higgs model with triplets that allows larger couplings and different WW/ZZ ratios, unlike pure doublet models.

Findings

hWW and hZZ couplings can be larger than in the Standard Model.

The ratio of hWW to hZZ couplings can differ from the Standard Model.

Collider rates for gg --> h --> WW and ZZ can be significantly enhanced.

Abstract

We study the couplings of a CP-even neutral Higgs boson h in a model containing one scalar SU(2)_L doublet, one real triplet, and one complex triplet with hypercharge 1. Because the two triplets contribute to the rho parameter with opposite signs, the triplet vacuum expectation values can be sizable. We show that (i) the hWW and hZZ couplings can be larger than the corresponding values in the Standard Model, and (ii) the ratio of the WW and ZZ couplings of h can be different than the corresponding ratio in the Standard Model. Neither of these results can occur in models containing only Higgs doublets. We also compute the rates for gg --> h --> WW and gg --> h --> ZZ and find that, for reasonable parameter values and M_h ~ 140-180 GeV, the hadron collider rate for gg --> h --> WW (ZZ) can be up to 20% (5 times) larger than in the Standard Model. We discuss implications for Higgs coupling extraction at the LHC.