PHYSICS PHD DISSERTATION DEFENSE: Jong Min Yoon

Ph.D. Candidate:  Jong Min Yoon
Research Advisor:  Michael E. Peskin

Date: Friday, May 24th, 2019
Time: 12:30pm
Location: B48/Madrone Conference Room at SLAC

Title: Toward a Predictive Composite Higgs Model: A Dual Approach in 5D

Abstract:
An interesting possibility of explaining the electroweak symmetry breaking is to consider the Higgs boson as a composite particle, i.e. a pseudo-Goldstone boson of a new strong dynamics. Although it is hard to make quantitative predictions under a strong interaction, we can use its dual description in 5D and compute physical observables. In this thesis, I introduce Gauge-Higgs unification models in warped 5-dimensional space as a setting for composite Higgs models. Gauge bosons and fermions are in the bulk and the Higgs boson is identified with the 5th component of a gauge field. We formalize the computation of the Coleman-Weinberg potential of the Higgs field and present a simple, general formula. Using this tool, we consider a specific model with SO(5)xU(1) global symmetry and introduce a new fermion multiplet, which competes with the top quark and creates a little hierarchy characterized by a small parameter s = v/f. Using a Green’s function method, we compute the properties of the model systematically as a power series in s. We discuss the constraints on this model from the measured value of the Higgs mass, the masses of top quark partners, and precision electroweak observables. Finally, we compute e+e- -> b bbar cross sections in general SO(5)xU(1) models. Our Green's function method provides an analytic understanding of the new physics effects across the parameter space. We find that the predicted effects will be visible in precision measurements and different models of b quark mass generation can be distinguished by these measurements already at 250 GeV in the center of mass.