Global Fits in the Supersymmetric Georgi-Machacek Model

Abstract

We study a supersymmetric extension of the SM with Higgs triplets in the scalar sector. We begin with a review of the SM, particularly the Higgs mechanism. In the SM, the Higgs mechanism requires the presence of a complex Higgs doublet to break the electroweak symmetry and endow particles with a mass; this process is called Electroweak Symmetry Breaking. Although this is the simplest possibility, higher scalar representations may also contribute to the EWSB. The extent to which these higher representations contribute to EWSB is constrained by precise measurements of the $rho$ parameter. The model must predict $ρ=1$ at tree level. It is a fortuitous circumstance that simple doublet representations satisfy this requirement exactly. The underlying reason is that models with doublets satisfy an accidental custodial symmetry. Therefore, one can add any number of scalar doublets and still satisfy this experimental constraint. For higher representations, it is a bit trickier to maintain the custodial symmetry. We study in this work a supersymmetric model that incorporates triplet representations and satisfies the custodial symmetry. The non-supersymmetric Gorgi-Machacek model is one example of a custodial invariant model of SSB with Higgs triplets. However, the GM model has a fine-tuning problem beyond that of the SM. The solution to both issues is the Supersymmetric Custodial Triplet Model. The supersymmetric GM model arises as a low energy limit of the SCTM. It is this model that we study here. We make use of public code, GMCalc and HiggsTools, to perform global fits to the parameters of this model and obtain limits on model parameters at the $95%$ confidence level. For these hypothetical scalars, we identify the dominant decay channels and extract bounds on their branching ratios. We also examine the possible presence of a 95 GeV Higgs Boson in the SGM.