UC Santa Cruz

In this dissertation, I explore the theory and prospects for generating the baryon asymmetry of the universe at the electroweak phase transition. Models of electroweak baryogenesis stand out among the possible explanations of the baryon asymmetry in that they can be conclusively probed by current experiments, such as collider, dark matter, and electric dipole moment (EDM) searches. After reviewing the mechanism of electroweak baryogenesis in superymmetric theories, I show that EWB is tightly constrained in the minimal supersymmetric extension of the Standard Model (MSSM) due to the apparent absence of light superpartners at the Large Hadron Collider (LHC), the non-observation of electric dipole moments, dark matter search results, and the discovery of a 125 GeV Standard Model-like Higgs. This suggests that electroweak baryogenesis, if realized in our universe, may require a non-minimal incarnation of supersymmetry. With this in mind, I then present a scenario for electroweak baryogenesis with an MSSM-like spectrum embedded in a Randall-Sundrum space-time. This model can accommodate a strongly first-order electroweak phase transition provided by the dynamics of the radion without light stops. In this case, CP-violating sources in the higgsino-gaugino sector can give rise to the observed baryon asymmetry and still be in agreement with constraints from dark matter and electric dipole moment searches. Finally, in the next-to-MSSM (NMSSM), I show that one can obtain a 125 GeV Higgs, a viable dark matter candidate with a 130 GeV gamma-ray line from the galactic center (as observed by the Fermi space telescope), and successful electroweak baryogenesis while satisfying all other relevant phenomenological constraints. A strongly first order electroweak phase transition can be realized in this case without a light stop. These novel possibilities are well-motivated and will be effectively probed by increased sensitivity in current experiments.