High-temperature QCD and the classical Boltzmann equation in curved   spacetime
  It has been shown that the high-temperature limit of perturbative thermal QCD is easily obtained from the Boltzmann transport equation for `classical' coloured particles. We generalize this treatment to curved space-time. We are thus able to construct the effective stress-energy tensor. We give a construction for an effective action. As an example of the convenience of the Boltzmann method, we derive the high-temperature 3-graviton function. We discuss the static case. 
F. T. Brandt, J. Frenkel and J. C. Taylor