The Three-Loop Free Energy for Pure Gauge QCD

We compute the free energy density for pure non-Abelian gauge theory at high temperature and zero chemical potential. The three-loop result to $O(g^4)$ is [a lovely formula. Get the paper and print it out.] We examine the sensitivity of this result to the choice of renormalization scale. We also give a result for the free energy of scalar $\phi^4$ theory, correcting a result previously given in the literature.