Effective potential at finite temperature in the standard model

There has been much recent interest in the nature of the electroweak phase transition. This information is of importance in the context of the sphaleron models that have recently been proposed to explain the observed net baryon number in the Universe. The presence of a term that is cubic in the Higgs condensate in the one-loop effective potential appears to indicate a first-order phase transition. However, the infrared singularities inherent in massless models produce cubic terms that are of the same order in the coupling. In this paper, we include these terms and show that the standard model has a first-order phase transition.