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Degree Name

Doctor of Philosophy (Ph.D.)




Joshua Erlich


We present new models of particle physics beyond the Standard Model. These models include extensions to the ideas of extra dimensions, deconstruction, supersymmetry, and Higgsless electroweak symmetry breaking. Besides introducing new models and discussing their consequences, we also discuss how galaxy cluster surveys can be used to constrain new physics beyond the Standard Model.;We find that an ultraviolet completion of gauge theories in the Randall-Sundrum model can be found in a deconstructed theory. The warping of the extra dimension is reproduced in the low energy theory by considering a general potential for the link fields with translational invariance broken only by boundary terms. The mass spectrum for the gauge and link fields is found to deviate from the Randall-Sundrum case after the first couple modes. By extending this model to a supersymmetric theory space, we find that supersymmetry is broken by the generation of a cosmological constant. Unless the theory is coupled to gravity or messenger fields, the spectrum remains supersymmetric.;We also present a hybrid Randall-Sundrum model in which an infinite slice of warped space is added to the extra dimension of the original theory. The hybrid model has a continuous gravitational spectrum with resonances at the Kaluza-Klein excitations of the original orbifolded model. A similar model is considered where the infinite space is cutoff by the addition of a negative tension brane. SU(2)L x SU(2)R x U(1)B-L gauge fields are added to the bulk of our hybrid model and we find that electroweak symmetry is broken with an appropriate choice of boundary conditions. By varying the size of the extra dimension, we find that the S parameter can be decreased by as much as 60%.;Finally we review models of structure formation and discuss the possibility of constraining new physics with galaxy cluster surveys. We find that for a large scatter in the luminosity-temperature relation, the cosmological parameters favored by galaxy cluster counts from the 400 Square Degree ROSAT survey are in agreement with the values found in the WMAP-3 year analysis. We explain why X-Ray surveys of galaxy cluster number counts are insensitive to new physics that would produce a dimming mechanism.



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