SEMIANALYTICAL APPROACHES TO LOCAL ELECTROWEAK BARYOGENESIS

We examine two semianalytical methods for estimating the baryon asymme try of the Universe (BAU) generated in scenarios of ''local'' electrow eak baryogenesis (in which the requisite baryon number violation and C P violation occur together in space and time). We work with the standa rd electroweak theory augmented by the addition of a CP-violating dime nsion-six operator. We work in the context of a first order phase tran sition, but the processes we describe can also occur during the evolut ion of a network of topological defects. Both the approaches we explor e deal with circumstances where the bubble walls which convert the hig h temperature phase to the low temperature phase are thin and rapidly moving. We first consider the dynamics of localized configurations wit h winding number one which remain in the broken phase immediately afte r the bubble wall has passed. Their subsequent decay can anomalously p roduce fermions. In a prelude to our analysis of this effect, we demon strate how to define the C and CP symmetries in the bosonic sector of the electroweak theory when configurations with nonzero winding are ta ken into account. Second, we consider the effect of the passage of the wall itself on configurations which happen to be near the crest of th e ridge between vacua as the wall arrives. We find that neither of the simple approaches followed here can be pushed far enough to obtain a convincing estimate of the BAU which is produced. A large scale numeri cal treatment seems necessary.