Date of Award
Doctor of Philosophy (PhD)
Ethan T. Neil
Thomas A. DeGrand
This thesis is about numerical simulations of a strongly coupled quantum field theory. The quantum field theory is a gauge theory based on the group SU(4) and contains fermionic matter charged under two different representations of the gauge group. The motivation for studying this theory is twofold. First, this theory is closely related to a theory of physics beyond the Standard Model which was recently proposed in the literature. In this model, the Higgs boson is a composite particle, and the top quark is a partially composite particle. Second, theories of this sort represent a new direction in the study of gauge dynamics and thus provide many opportunities to test our qualitative understanding of strongly coupled physics. The main result of this thesis is direct, non-perturbative (albeit numerical) calculation of the particle spectrum of the theory, including both mesons and baryons. Briefly stated, the particle spectrum turns out to be quite similar to that of QCD.
The first three chapters of the thesis serve as a theoretical background. Aside from incidental remarks, the material in these sections appears in standard references. The final four chapters deal with the numerical simulations and contain the new scientific contributions of this thesis. The main results of the thesis are: the low-energy constants associated with the pseudoscalar mesons (found in Table 5.1); estimates of the width-to-mass ratios of the vector mesons (found in Figure 5.14); and the full meson and baryon spectrum in physical units (found in Figure 6.10). For the reader already familiar with lattice techniques, Sections 5.4 and 6.9 provide compact summaries of the techniques and results for the meson and baryon spectrum.
Jay, William I., "Beyond the Standard Model with Composite Particles: a Lattice Study Based on SU(4)" (2018). Physics Graduate Theses & Dissertations. 251.