Dark Matter in Beyond the Standard Model Physics
Date
2024
Authors
Leerdam, Nicholas Dean
Editors
Advisors
White, Martin
Williams, Anthony
Williams, Anthony
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Thesis
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Abstract
Physics has a remarkable ability to explain a wide variety of phenomena observed in the universe using only a small number of fundamental theories. The Standard Model covers the behaviour and interactions of subatomic particles, and its predictions match experimental results to the highest precision possible. At the other end of the scale, General Relativity explains the dynamics of galaxies and the universe itself, and has never been wrong in any of its predictions. These seemingly far-away theories can even be applicable to things we observe in our every day life. Newtonian physics emerges as a limit of general relativity when objects are small and travel slowly, and classical mechanics is a limit of quantum mechanics for objects made from many quantum particles. Such is the accuracy and broad applicability of these theories that they are accepted to be ‘true’, meaning as best we know their theoretical design reflects the true nature of our universe. There are only a small number of observations that these theories cannot explain. One of the aims of physics is to find a conclusive explanation for these unexplained phenomena, through extending the existing theories. This pursuit is captured by the field of Beyond the Standard Model physics, and the nature of dark matter is one of the most well known problems. There are actually many ways to make extensions to the Standard Model or General Relativity to explain dark matter (and other unexplained observations). But this doesn’t solve the problem satisfactorily. We must also understand why it should be one way instead of another, and seek answers that don’t require specific, and unlikely, circumstances. Modern physics also considers these philosophical questions and tries to answer them with a rigorous, mathematical, evidence-based framework. The far-away goal is a single, natural theory that is single-handedly able to explain every phenomena. This thesis presents only a few of the multitude of proposed theories and ideas. As well as dark matter, the following theories incorporate aspects of other unexplained phenomena. In chapter 3, we present a family of models that addresses both dark matter and the origins of neutrino mass, and provide an in-depth analysis for two of them. In chapter 4, we cover theoretical explanations combining inelastic dark matter with two possible unexplained phenomena - the 21cm absorption signal observed by the EDGES experiment, and the XENON1T electron excess. In chapter 5 we analyse the solution of Boltzmann equations for general dark matter distributions. Finally in chapter 6, we summarise the specifics of axion electrodynamics, which could potentially explain both dark matter and the strong CP problem.
School/Discipline
School of Physics, Chemistry and Earth Sciences : Physics
Dissertation Note
Thesis (Ph.D.) -- University of Adelaide, School of Physics, Chemistry and Earth Sciences : Physics, 2024
Provenance
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