A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, December 2014. / In this thesis the evolution equations of the Yukawa couplings and quark flavour
mixings are derived for the one-loop renormalisation group equations in five
and six-dimensional models, compactified in different possible ways to yield
standard four space-time dimensions. Different possibilities for the matter
fields are discussed, such as the case of bulk propagating or brane localized
fields. We discuss in both cases the evolution of the Yukawa couplings, the Jarlskog
parameter and the Cabibbo-Kobayashi-Maskawa matrix elements, finding
that for both scenarios, as we run up to the unification scale, significant
renormalisation group corrections are present. We also discuss the results of
different observables of the five-dimensional universal extra dimension model
in comparison with those of six-dimensional models and the model dependence
of the results. We also studied the scaling of the mass ratios and the implications
for the mixing angles in these six-dimensional model as well as the 5D
Minimal Supersymmetric Standard Model on an S1/Z2 orbifold.
The renormalisation group equation evolutions for the Higgs sector and for
the neutrino sector in six-dimensional models are also investigated. The recent
experimental results of the Higgs boson from the LHC allow, in some scenarios,
stronger constraints on the cutoff scale to be placed, from the requirement of
the stability of the Higgs potential.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/17656 |
| Date | 07 May 2015 |
| Creators | Abdalgabar, Ammar Ibrahim |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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