$\Phi$-derivable approximations in gauge theories

Abstract

We discuss the method of $\Phi$-derivable approximations in gauge theories. There, two complications arise, namely the violation of Bose symmetry in correlation functions and the gauge dependence. For the latter we argue that the error introduced by the gauge dependent terms is controlled, therefore not invalidating the method.

5 pages, 4 small figures, to appear in the proceedings of SEWM 2002