Higgs production at future e+e\u2212 colliders in the Georgi-Machacek model

Abstract

We study how the dominant single and double SM-like Higgs (h) production at future e+e− colliders is modified in the Georgi-Machacek (GM) model. On imposing theoretical, indirect and direct constraints, significant deviations of h-couplings from their SM values are still possible; for instance, the Higgs-gauge coupling can be corrected by a factor κhV V ∈ [0.93, 1.15] in the allowed parameter space. For the Higgs-strahlung e+e− → hZ and vector boson fusion processes {e}^{+}{e}^{-}to hnu overline{nu} , he+e−, the cross section could increase by 32% or decrease by 13%. In the case of associated production with a top quark pair {e}^{+}{e}^{-}to htoverline{t} , the cross section can be enhanced up to several times when the custodial triplet scalar H30 is resonantly produced. In the meanwhile, the double Higgs production {e}^{+}{e}^{-}to hhZleft(hhnu overline{nu}right) can be maximally enhanced by one order of magnitude at the resonant H1,30 production. We also include exclusion limits expected from future LHC runs at higher energy and luminosity and discuss their further constraints on the relevant model parameters. We find that the GM model can result in likely measurable deviations of Higgs production from the SM at future e+e− colliders.