EFFECTIVE COUPLING CONSTANTS IN GAUGE THEORIES AT HIGH TEMPERATURE

Abstract

High temperature behavior of the effective gauge coupling constants, defined through the effective Lagrangians L(H, T) of strong magnetic field H=const, is investigated for a number of models. In spinor QED the well-known zero charge behavior is realized in the limit T≫(gH)1/2>μ, μ is subtraction point in the field. In scalar QED in addition to logarithmic term ~ln T/T0 describing the zero charge, the term ~T/(gH)1/2 appears and dominates at high temperatures. Similar terms are also present in the non-Abelian models and spoil asymptotic freedom of perturbative vacuum. In the latter models, the linear in T terms are resulted in the generation of classical homogeneous magnetic fields. At this background asymptotic freedom is restored.