Partial Path Integration of Quantum Fields: Two-Loop Analysis of the SU(2) Gauge-Higgs Model at Finite Temperature

High temperature reduction of the SU(2) Higgs model is realised by partially integrating its partition function. Various approximate forms of the effective theory resulting from the integration over nonstatic fields and the static electric potential are analysed. Also non-polynomial and non-local terms are allowed. Consistency of the perturbative solution is ensured by new types of induced counterterms. Perturbative phase transition characteristics are presented in the Higgs mass range 30-120 GeV, and compared to results of other perturbative approaches.