Operator analysis for the Higgs potential and cosmological bound on the Higgs-boson mass

Using effective-field theory at finite temperature, we examine the impact of new physics on the electroweak phase transition. By analyzing the high-dimensional operators relevant to the Higgs potential we point out that the Higgs-boson mass bound obtained by avoiding the washout of the baryon asymmetry can be relaxed to the region allowed by experiments, provided that new physics appears at the TeV scale.