Higgs couplings in a model with triplets

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 ρ 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 Mₕ~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.