SU(2) Yang-Mills thermodynamics: Two-loop corrections to the pressure

We compute the two-loop corrections to the thermodynamical pressure of an SU(2) Yang-Mills theory being in its electric phase. Our results prove that the one-loop evolution of the effective gauge coupling constant is reliable for any practical purpose. We thus establish the validity of the picture of almost noninteracting thermal quasiparticles in the electric phase. Implications of our results for the explanation of the large-angle anomaly in the power spectrum of temperature fluctuations in the cosmic microwave background are discussed.