Particle physics models at the electroweak scale and beyond

We consider various particle physics models constructed to address issues in electroweak-scale supersymmetry, grand unification, and inflation. We begin by exploring the phenomenology of a supersymmetric SU(5) theory living in a truncated, warped 5-dimensional spacetime, with the gauge group broken down to the Standard Model at both ends. The low-energy spectrum of this setup is exotic, and in particular includes a particle of O (TeV) mass with the quantum numbers of an off diagonal SU(5) adjoint. Via the AdS/CFT correspondence, this is interpreted as a pseudo-Goldstone boson of a broken global symmetry within the strongly-coupled sector responsible for supersymmetry breaking. We consider the phenomenology of such a particle in some detail, including collider signals and cosmology. We proceed to consider a generic framework for ameliorating fine-tuning in the Minimal Supersymmetric Standard Model, utilizing new contributions to the Higgs boson mass. We demonstrate this idea with two explicit models. Returning to warped spacetime, we then demonstrate the feasibility of applying AdS/CFT ideas to the breaking of grand unified theories. In this context, the warped spacetime description is dual to a strong gauge sector which develops condensates and breaks the unified gauge group into which the Standard Model is embedded. Finally, we consider the generation of primordial density perturbations in the model of chain inflation, utilizing a combination of analytic and numerical techniques.