Transport coefficients from the 2PI effective action: weak coupling and large N analysis

Abstract

The diagrammatic computation of transport coefficients in relativistic field theories is discussed. We show that the lowest nontrivial truncation of the two-particle irreducible (2PI) effective action correctly determines transport coefficients in a weak coupling or 1/N expansion at leading (logarithmic) order. In gauge theories, we verify gauge fixing independence and consistency with the Ward identity. These results support the applicability of 2PI effective action techniques to the study of nonequilibrium quantum-field dynamics.