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UBC Theses and Dissertations

Particle phenomenology at the frontiers Winslow, Peter


The Standard Model of particle physics has proven itself as a wildly successful description of the microscopic world. Yet, despite all its accomplishments, deep mysteries remain for which the Standard Model offers no explanation. This thesis is dedicated to the phenomenological study, as well as the creation of, a number of well-motivated extensions to the Standard Model, each originally designed to explain a known flaw. The Randall-Sundrum model employs an extra dimension to exponentially suppress all mass scales in the theory, generating the electroweak-Planck hierarchy with no recourse to fine-tuning of parameters. In this way, it can lead to unwanted enhancements of higher dimensional operators inducing strongly constrained processes such as proton decay. We investigate the effects of the Randall-Sundrum model on a similar process, neutron-antineutron oscillation, and find that, in contrast to the example of proton decay, it is naturally suppressed below experimental limits by virtue of the flavor structure of the operators inducing it. The DZero collaboration has reported strong evidence of CP violation beyond the Standard Model in measurements of the like-sign dimuon asymmetry at the Tevatron. The nature of the signal suggests the presence of new physics in the form of new bosonic particles with weak scale masses and new sources of CP violation in the mixing of neutral B mesons. We note that this is exactly what is needed for viable electroweak baryogenesis in extensions of the Standard Model. We explore the potential for simultaneously explaining the dimuon asymmetry and the baryon asymmetry of the Universe using a Two-Higgs-Doublet-Model with an unusual flavor structure. Both the CDF and DZero collaborations measure a strong preference for top quarks, produced in pairs at the Tevatron, to propagate in the direction of the initial proton beam, in direct conflict with Standard Model predictions. A class of new physics models with novel flavor interactions has been proposed to explain this behaviour through a Rutherford enhancement in the forward direction. We show that such interactions can also simultaneously explain a long-standing tension between different measurements of the CKM matrix element Vub through the generation of large loop-induced right-handed charge currents.

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