Contour Diagrammatic Structure in Terms of Functional Derivatives
Abstract
This chapter considers the procedure originally due to Schwinger, which sets up a number of exact coupled integral equations satisfied by the Green’s functions, avoiding in this way expansions in powers of the coupling constant. This procedure relies on the source field method, where a functional differentiation with respect to a source field is suitably exploited. Specifically, this procedure is here considered for the time-dependent (nonequilibrium) case.
Fields of Study & Subjects
Quantum and Classical Electrodynamics
Quantum Chromodynamics and Particle Interactions
Particle physics theoretical and experimental studies
Publication details
- Journal / source
- Cambridge University Press eBooks
- Pages
- 135–144
- Publication date
- 6 February 2026
- Document type
- Book chapter