NONLOCAL ELECTROWEAK BARYOGENESIS .1. THIN WALL REGIME

We investigate ''nonlocal'' schemes for baryogenesis at a first-order electroweak phase transition, in which the effects of a CP-violating c ondensate on the bubble wall propagate into the unbroken phase where t he sphaleron rate is unsuppressed. Such a condensate exists in multi-H iggs-boson extensions of the standard model, and may exist due to an i nstability in the minimal standard model. In this paper we first discu ss the general problem of determining the perturbations induced by a C P-violating condensate, distinguishing two regimes (quantum and classi cal). We then give an analytic treatment of quantum-mechanical reflect ion in the thin wall regime, in which interactions with the plasma can be neglected as a particle propagates across the wall. We focus on le ptons because of their much weaker coupling to the plasma. We argue th at they are likely to be accurately described by this calculation, but quarks are not. The relative magnitude of the baryon asymmetry produc ed for different fermions depends on their relative Yukawa couplings ( not their zero temperature masses), their transport properties, and th eir interactions. We calculate the baryon asymmetry for various parame ter ranges and conclude that asymmetries comparable with observations can be generated.