Theoretical description of time-resolved photoemission spectroscopy: application to pump-probe experiments

The theory for time-resolved photoemission spectroscopy as applied to pump-probe experiments is developed and solved for the generic case of a strongly correlated material. The formal development incorporates all of the nonequilibrium effects of the pump pulse and the finite time width of the probe pulse. While our formal development is completely general, in our numerical illustration for the Hubbard model, we assume the pump pulse drives the electrons into a nonequilibrium configuration, which rapidly thermalizes to create a hot (quasi-equilibrium) electronic system, and we then study the effects of windowing that arise from the finite width of the probe pulse. We find sharp features in the spectra are broadened, particularly the quasiparticle peak of strongly correlated metals at low temperature.