Supersymmetric electroweak baryogenesis

We calculate the baryon asymmetry generated at the electroweak phase transi tion in the minimal supersymmetric standard model, using a new method to co mpute the CP-violating asymmetry in the Higgsino flux reflected into the un broken phase. The method is based on a Higgs insertion expansion. We find t hat the CP asymmetry at leading order is proportional to the change in tan beta in the bubble wail, which is at most of order 10(-2), while at next-to -leading order this suppression factor disappears. This result may enhance the final baryon asymmetry generated during the electroweak phase transitio n for small Delta beta (< 10(-3)). (C) 2000 Elsevier Science B.V. All right s reserved.