Z(N) interface tension in a hot SU(N) gauge theory
  The interface tension between Z(N) vacua in a hot SU(N) gauge theory (without dynamical fermions) is computed at next to leading order in weak coupling. The Z(N) interface tension is related to the instanton of an effective action, which includes both classical and quantum terms; a general technique for treating consistently the saddle points of such effective actions is developed. Loop integrals which arise in the calculation are evaluated by means of zeta function techniques. As a byproduct, up to two loop order we find that the stable vacuum is always equivalent to the trivial one, and so respects charge conjugation symmetry. 
T. Bhattacharya, A. Gocksch, C. P. Korthals-Altes, and R. D. Pisarski