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UBC Theses and Dissertations

Quark nugget dark matter : cosmic evidence and detection potential Lawson, Kyle


I present a dark matter model in which the dark matter is composed of very heavy “nuggets” of Standard Model quarks and antiquarks. This model was originally motivated by the fact that the matter and dark matter mass densities are observed to have similar scales. If these two forms of matter originate through completely distinct physical processes then their densities could easily have existed at vastly different scales. However, if the dark and the visible matter are co-produced, this similarity in scales is a natural outcome. In the model considered here dark matter and the baryonic matter share an origin in Standard Model strong force physics. The main goal of this work is to establish the testable predictions of this model. The physical properties of the nuggets are set by well understood nuclear physics and quantum electrodynamics, allowing many observable consequences to be predicted. To this end, I devote special attention to the structure of the surface layer of the nuggets from which the majority of observable consequences arise. With this basic picture of nugget structure in place, I will discuss the consequences of their interactions with a number of different environments. Particular attention is given to the galactic centre and to the early universe, as both are sufficiently dense to allow for significant levels of matter-dark matter interaction. The emitted radiation, in both cases, is shown to be consistent with observations. Finally, I discuss the consequences of a nugget striking the earth. In this context, I will demonstrate that the nuggets produce effects observable in cosmic ray detectors. Based on these considerations, I discuss the nugget detection potential for experiments primarily devoted to the study of high energy cosmic rays.

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