We apply the concept of reflection-transmission (RT) algebra, originally developed in the context of integrable systems in 1+1 space-time dimensions, to the study of finite temperature quantum field theory with impurities in higher dimensions. We consider a scalar field in (s + 1) + 1 space-time dimensions, interacting with impurities localized on s-dimensional hyperplanes, but without self-int...

We review different aspects of field theory at zero and finite temperature, related to the theory of phase transitions. We discuss different renormalization conditions for the effective potential at zero temperature, emphasizing in particular the MS renormalization scheme. Finite temperature field theory is discussed in the real and imaginary time formalisms, showing their equivalence in simple...

I discuss three subjects in thermal field theory: why in SU(N) gauge theories the Z(N) symmetry is broken at high (instead of low) temperature, the possible singularity structure of gauge variant propagators, and the problem of how to compute the viscosity from the Kubo formula. Based on an invited talk presented at the Workshop on Hot QCD held at the Winnipeg Institute for Theoretical Physics,...

We discuss a few selected topics in finite temperature field theory.