Change timing: seminar on Thursday

[Cond.Matt. & Stat.Mech.Section]

 Please note TIME change
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SEMINAR on   Disorder and strong electron correlations

 

Thursday, 16 May -    1:45 p.m.

 ________________________



Luigi Stasi Seminar Room,  Leonardo Building - first floor

 

Jürgen BERGES   (Universität Heidelberg)

 

"Functional renormalization group  in and out of equilibrium"

 

Abstract


For quantum systems specified by a given density matrix at initial time, a generating functional for real-time correlation functions can be written down using the Schwinger-Keldysh closed time path. This can be used to construct a nonequilibrium functional renormalization group along similar lines as for Euclidean field theories in thermal equilibrium.  Important differences include the absence of a fluctuation-dissipation relation for general out-of-equilibrium situations.  The nonequilibrium renormalization group takes on a particularly simple form at a fixed point, where the corresponding scale-invariant system becomes independent of the details of the initial density matrix.  This can be used to derive a hierarchy of fixed point solutions with increasing complexity from vacuum and thermal equilibrium to nonequilibrium.  The application to dynamic critical phenomena and the phenomenon of turbulence in quantum field theory will be discussed.