Baryogenesis

It now seems plausible that the observed baryon asymmetry may have been produced at the electroweak phase transition. We review the considerations which lead to this conclusion, focusing on the obstacles to making reliable estimates. These arise from incomplete knowledge of baryon-violating rates near the phase transition, our limited understanding of the phase transition itself, and incomplete understanding of the mechanisms which actually lead to an asymmetry.

The status of electroweak baryogenesis in the minimal supersymmetric standard model is reviewed. I discuss the strength of the phase transition, CP violation and transport at the bubble walls, and the possibility of a two stage transition involving charge and color breaking.

We present a novel scenario for baryogenesis in a hybrid inflation model at the electroweak scale, in which the Standard Model Higgs field triggers the end of inflation. One of the conditions for successful baryogenesis, the departure from thermal equilibrium, is naturally achieved at the stage of preheating after inflation. The inflaton oscillations induce large occupation numbers for long-wavelength configurations of Higgs and gauge fields, which leads to a large rate of sp...

Electroweak baryogenesis (EWBG) remains a theoretically attractive and experimentally testable scenario for explaining the cosmic baryon asymmetry. We review recent progress in computations of the baryon asymmetry within this framework and discuss their phenomenological consequences. We pay particular attention to methods for analyzing the electroweak phase transition and calculating CP-violating asymmetries, the development of Standard Model extensions that may provide the n...

The physics of electroweak baryogenesis is described with the aim of making the essentials clear to non-experts. Several models for the source of the necessary CP violation are discussed: CKM phases as in the minimal standard model, general two higgs doublet models, the supersymmetric standard model, $Z$ condensates, and the singlet majoron model. In a more technical section, a strategy is introduced for consistently treating quark dynamics in the neighborhood of the bubble w...

There are many reasons to believe that there might be new sources of CP-violation beyond the phases of the KM matrix. One of these is the possibility of electroweak baryogenesis. We describe some recent developments in this subject and make some comments on the possibility that the minimal standard model might itself be the origin of the baryon asymmetry. To appear in the Proceedings of the Third KEK Topical Conference on CP Violation, its Implications to Particle Physics and...

In the standard model and most of its extensions the electroweak transition is too weak to affect the cosmological baryon asymmetry. Due to sphaleron processes baryogenesis in the high-temperature, symmetric phase of the standard model is closely related to neutrino properties. The experimental indications for very small neutrino masses from the solar and the atmospheric neutrino deficits favour a large scale of B-L breaking. For hierarchical neutrino masses, with B-L broken ...

We investigate `non-local' schemes for baryogenesis at a first order electroweak phase transition, in which the effects of a $CP$ violating condensate on the bubble wall propagate into the unbroken phase where the sphaleron rate is unsupressed. Such a condensate exists in multi-Higgs extensions of the standard model, and may exist due to an instability in the minimal standard model. In this paper we first discuss the general problem of determining the $CP$ violating perturbat...

We show that a cosmological baryon asymmetry generated at the GUT scale, which would be destroyed at lower temperatures by sphalerons and possible new B- or L-violating effects, can naturally be preserved by an asymmetry in the number of right-handed electrons. This results in a significant softening of previously derived baryogenesis-based constraints on the strength of exotic B- or L-violating interactions.

We describe a new mechanism for the generation of the baryon asymmetry of the universe during a first order electroweak phase transition. The mechanism requires the existence of two (or more) baryon number carrying scalar fields with masses and CP violating mixing which vary with the Higgs field expectation value. This mechanism can be implemented using squarks in supersymmetric theories or using leptoquarks. Our central observation is that reflection of these scalars from a ...