Subject Area
Physics
Abstract
In this dissertation, we study a supersymmetric extension of the Standard Model with Higgs triplets in the scalar sector. We begin with a review of the Standard Model (SM), particularly the electroweak sector and 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 Spontaneous Symmetry Breaking (SSB). Although this is the simplest possibility, higher scalar representations may also contribute to the electroweak breaking process (EWSB). The extent to which these higher representations contribute to EWSB is constrained by precise measurements of the ρ 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, satisfies the custodial symmetry, and predicts ρ ≈ 1 at tree level. The non-supersymmetric Georgi-Machacek (GM) 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 (SCTM). The supersymmetric Georgi-Machacek model arises as a low energy limit of the SCTM model. 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 strong limits on the triplet vacuum expectation values, mixing angles, mass differences between the new heavy exotic Higgs bosons, as well as their decay width, at the 95% confidence level. For these new hypothetical scalars, we identify the dominant decay channels and extract bounds on their branching ratios from the global fits. We also examine the possible presence of a 95 GeV Higgs Boson in the SGM model.
Degree Date
Spring 5-11-2024
Document Type
Dissertation
Degree Name
Ph.D.
Department
Physics
Advisor
Roberto Vega
Number of Pages
104
Format
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License
Recommended Citation
Xu, Yingnan, "Global Fits In The Supersymmetric Georgi-Machacek Model" (2024). Physics Theses and Dissertations. 18.
https://scholar.smu.edu/hum_sci_physics_etds/18
