ELECTROWEAK BARYOGENESIS IN THE NEXT TO MINIMAL SUPERSYMMETRIC MODEL

In the electroweak phase transition there arises the problem of baryon number washout by sphaleron transitions, which can be avoided if the phase transition is strongly enough first order. The minimal supersymm etric standard model has just two Higgs doublets H-1 and H-2, while th e next to minimal model, NMSSM, has an additional singlet, N, this lat ter giving rise to the helpful feature that the Higgs potential contai ns a tree level trilinear field term. We use the tunneling criterion f or the existence of a first order electroweak phase change. A quantita tive statistical analysis indicates that with parameters of the NMSSM satisfying the experimental constraints a strong first order phase cha nge occurs in about 50% of cases.