Properties of multi-particle Green's and vertex functions within Keldysh formalism
Jakobs, Severin G; Pletyukhov, Mikhail; Schoeller, Herbert; Jakobs, Severin G; Institut für Theoretische Physik A, RWTH Aachen University, D-52056 Aachen, Germany; JARA—Fundamentals of Future Information Technology, Aachen and Jülich, Germany; Pletyukhov, Mikhail; Institut für Theoretische Physik A, RWTH Aachen University, D-52056 Aachen, Germany; JARA—Fundamentals of Future Information Technology, Aachen and Jülich, Germany; Schoeller, Herbert; Institut für Theoretische Physik A, RWTH Aachen University, D-52056 Aachen, Germany; JARA—Fundamentals of Future Information Technology, Aachen and Jülich, Germany
Журнал:
Journal of Physics A: Mathematical and Theoretical
Дата:
2010-03-12
Аннотация:
The increasing interest in nonequilibrium effects in condensed matter theory motivates the adaption of diverse equilibrium techniques to Keldysh formalism. For methods based on multi-particle Green's or vertex functions, this involves a detailed knowledge of the real-time properties of those functions. In this review, we derive general properties of fermionic and bosonic multi-particle Green's and vertex functions for a stationary state described within Keldysh formalism. Special emphasis is put on the analytic properties associated with causality and on a detailed discussion of the Kubo–Martin–Schwinger conditions which characterize thermal equilibrium. Finally we describe how diagrammatic approximations and approximations within the functional renormalization group approach respect these properties.
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