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I will discuss the real-time dynamics of interacting electrons
that are described by Hubbard-type models. This is of interest
to describe the electronic relaxation on femtosecond timescales
in pump-probe experiments on strongly correlated materials,
and can also apply to experiments with cold atomic gases. In
both situations an essentially isolated quantum-mechanical
many-body system is forced out of equilibrium and relaxes to
a new stationary state, which is not necessarily the thermal
state predicted by statistical mechanics. I will discuss how
nonequilibrium Green functions for Hubbard-type models can be
obtained using dynamical mean-field theory, and how they are
related to time-resolved photoemission and optical spectra.
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