PUB - Publikationen an der Universität Bielefeld

We study the universality class and critical properties of the electroweak theory at finite temperature. Such critical behaviour is found near the endpoint m(H) = m(H,c) of the line of first-order electroweak phase transitions in a wide class of theories, including the Standard Model (SM) and a part of the parameter space of the Minimal Sypersymmetric Standard Model (MSSM). We find that the location of the endpoint corresponds to the Higgs mass m(H,c) = 72(2) GeV in the SM with sin(2) theta(w) = 0, and m(H,c) < 80 GeV with sin(2) theta(w) = 0.23. As experimentally m(H) > 88 GeV, there is no electroweak phase transition in the SM. We compute the corresponding critical indices and provide strong evidence that the phase transitions near the endpoint fall into the three-dimensional Ising universality class. (C) 1998 Elsevier Science B.V.