Far-from-equilibrium quantum many-body dynamics
Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16, 69120, Heidelberg, Germany
2 ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291, Darmstadt, Germany
3 Institut für Theoretische Physik, Universität Erlangen-Nürnberg, Staudtstr. 7, 91058, Erlangen, Germany
Published online: 16 September 2010
A theory of real-time quantum many-body dynamics is evaluated in detail. It is based on a generating functional of correlation functions where the closed time contour extends only to a given time. Expanding the contour from this time to a later time leads to a dynamic flow of the generating functional. This flow describes the dynamics of the system and has an explicit causal structure. In the present work it is evaluated within a vertex expansion of the effective action leading to time-evolution equations for Green functions. These equations are applicable for strongly interacting systems as well as for studying the late-time behavior of non-equilibrium time evolution. For the specific case of a bosonic -component φ 4-theory with contact interactions an s-channel truncation is identified to yield equations identical to those derived from the 2PI effective action in next-to-leading order of a expansion. The presented approach allows to directly obtain non-perturbative dynamic equations beyond the widely used 2PI approximations.
© Springer-Verlag / Società Italiana di Fisica, 2010