Fading of symmetry nonrestoration at finite temperature - art. no. 025008

The fate of symmetries at high temperature determines the dynamics of the v ery early universe. It is conceivable that temperature effects favor symmet ry breaking instead of restoration. Concerning global symmetries, the nonli near sigma model is analyzed in detail. For spontaneously broken gauge symm etries, we propose the gauge boson magnetic mass as a "flag" for symmetry ( non)restoration. We consider several cases: the standard model with one and two Higgs doublers in the perturbative regime and the case of a strongly i nteracting Higgs sector. The latter is done in a model-independent way with the tools provided by chiral Lagrangians. Our results clearly point toward s restoration, a pattern consistent with recent lattice computations for gl obal symmetries. In addition, we explicitly verify Becchi-Rouet-Stora-Tyuti n invariance for gauge theories at finite temperature. [S0556-2821(98)03518 -8].