Particle Physics in the Randall-Sundrum Framework

Abstract

In this dissertation, several aspects of particle physics in the Randall-Sundrum framework are discussed. We view the Randall-Sundum framework as a model for the dual of a strongly interacting technicolor theory of electroweak symmetry breaking (EWSB). First, we consider extra dimensional descriptions of models where there are two separate strongly interacting EWSB sectors ("topcolor" type models). Such models can help alleviate the tension between the large top quark mass and the correct value of the Zbb couplings in ordinary Higgsless models. A necessary consequence is the appearance of additional pseudo-Goldstone bosons ("top-pions"), which would be strongly coupled to the third generation. Second, we examine extra-dimensional theories as "AdS/QCD" models of hadrons, pointing out that the infrared physics can be developed in a more systematic manner by exploiting backreaction of the nonperturbative condensates. We also show how asymptotic freedom can be incorporated into the theory, and the substantial effect it has on the glueball spectrum and gluon condensate of the theory. Finally, we study the S parameter, considering especially its sign, in models with fermions localized near the UV brane. We show that for EWSB in the bulk by a Higgs VEV, S is positive for arbitrary metric and Higgs profile, assuming that the effects from higher-dimensional operators in the 5D theory are sub-leading and can therefore be neglected. Our work strongly suggests that S is positive in calculable models in extra dimensions.