Higgs production at future $e^+e^-$ colliders in the Georgi-Machacek model

TL;DR

This paper investigates how the Georgi-Machacek model alters Higgs production at future electron-positron colliders, revealing potential measurable deviations from Standard Model predictions across various production channels.

Contribution

It provides a detailed analysis of Higgs production modifications in the GM model, including constraints and potential experimental signatures at future colliders.

Findings

Higgs-gauge coupling can vary between 0.93 and 1.15 times the SM value.

Cross sections for certain processes can increase by up to 32% or decrease by 13%.

Double Higgs production can be enhanced by up to an order of magnitude.

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 coupling can be corrected by a factor $\kappa_{hVV}\in[0.93,1.15]$ in the allowed parameter space. For the Higgs-strahlung $e^+e^-\to hZ$ and vector boson fusion processes $e^+e^-\to h\nu\bar{\nu},~he^+e^-$, the cross section could increase by $32\%$ or decrease by $13\%$. In the case of associated production with a top quark pair $e^+e^-\to ht\bar{t}$, the cross section can be enhanced up to several times when the custodial triplet scalar $H_3^0$ is resonantly produced. In the meanwhile, the double Higgs production $e^+e^-\to hhZ~(hh\nu\bar{\nu})$ can be maximally enhanced by one order of magnitude at the resonant $H_{1,3}^0$ 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.