Parquet theory for correlated thermodynamic Greens functions

Abstract

We address the problem of finding self-consistent parquet equations for two-body correlated Greens functions that arise out of a cumulant expansion. The general theory as developed for non-relativistic electron systems reproduces the conventional two-body parquet diagrammatic technique for the vertex functions. As an application, the crossing-invariant linearized basic parquet equations are treated for the correlated two-particle Greens function. It is pointed out that besides the Cooperon there are two additional prominent crossingsymmetric two-particle channels in many-particle systems with pair interaction.