Electroweak phase transition and Higgs boson couplings in the model based on supersymmetric strong dynamics

TL;DR

This paper explores a supersymmetric strong dynamics model with an extended Higgs sector, demonstrating that it can produce a strongly first-order electroweak phase transition suitable for baryogenesis, and predicts observable deviations in Higgs couplings.

Contribution

It introduces a low-energy effective theory based on supersymmetric SU(2) gauge dynamics that achieves a strong electroweak phase transition and predicts measurable Higgs coupling deviations.

Findings

Electroweak phase transition can be strongly first order in this model.

Higgs-to-diphoton rate is about 20% smaller than SM.

Triple Higgs coupling is more than 20% larger than SM.

Abstract

We discuss a strongly-coupled extended Higgs sector with the 126 GeV Higgs boson, which is a low-energy effective theory of the supersymmetric SU(2)$_H$ gauge thoery that causes confinement. In this effective theory, we study the parameter region where electroweak phase transition is of strongly first order, as required for successful electroweak baryogenesis. In such a parameter region, the model has a Landau pole at the order of 10 TeV, which corresponds to the confinement scale of the SU(2)$_H$ gauge theory. We find that the large coupling constant which blows up at the Landau pole results in large non-decoupling loop effects on low-energy observables, such as the Higgs-photon-photon vertex and the triple Higgs boson vertex. As phenomenological consequences of electroweak baryogenesis in our model, the Higgs-to-diphoton branching ratio is about 20% smaller while the triple Higgs boson coupling is more than about 20% larger than the standard model predictions. Such deviations may be detectable in future collider experiments.