Effect of dynamical spectral weight redistribution on effective   interactions in time-resolved spectroscopy
  The redistribution of electrons in an ultrafast pump-probe experiment causes significant changes to the effective interaction between electrons and bosonic modes. We study the influence of these changes on pump-probe photoemission spectroscopy for a model electron-phonon coupled system using the nonequilibrium Keldysh formalism. We show that spectral rearrangement due to the driving field preserves an overall sum rule for the electronic self-energy, but modifies the effective electron-phonon scattering as a function of energy. Experimentally, this pump-modified scattering can be tracked by analyzing the fluence or excitation energy dependence of population decay rates and transient changes in dispersion kinks. 
A.F. Kemper, M.A. Sentef, B. Moritz, J.K. Freericks and T.P. Devereaux
cond-mat.mes-hall cond-mat.mtrl-sci