We present a detailed analysis of the phase transition in the standard model at finite temperature. Using an improved perturbation theory, where plasma masses are determined from a set of one-loop gap equations, we evaluate the effective potential Veff(φ, T) in next-to-leading order, i.e., including terms cubic in the gauge coupling g, the scalar self-coupling λ1/2, and the top-quark Yukawa coupling ft. The gap equations yield a non-vanishing magnetic plasma mass for the gauge bosons, originating from the non-abelian self-interactions. We discuss in detail size and origin of higher order effects and conclude that the phase transition is weakly first-order up to Higgs masses of about 70 GeV, above which our calculation is no longer self-consistent. For larger Higgs masses even an approximation containing all g4 contributions to Veff is not sufficient, at least a full calculation to order g6 is needed. These results turn out to be rather insensitive to the top-quark mass in the range mtop = 100-180 GeV. Using Langer′s theory of metastability we calculate the nucleation rate of critical droplets and discuss some aspects of the cosmological electroweak phase transition.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)