Dissipative thermal field theory and renormalization

Using methods of thermo field dynamics we develop a perturbation and renormalization procedure for thermally dissipative quantum fields. We emphasize the need to construct dissipative asymptotic fields and to treat the dissipation self consistently. From a stationarity condition we find the Bose-Einstein distribution for the number density in the zero dissipation limit. Considering a simple model with symmetry breaking we find that Goldstone's theorem is satisfied and at zero energy the Goldstone boson does not interact or dissipate, even though at finite momentum and energy the particles are dissipating. The theory should find uses in any physical process involving thermal effects.