Quantum kinetic equations: Correlation dynamics and selfenergy

The derivation of non-Markovian quantum kinetic equations is reconsidered in the framework of density operators. Conventional derivations use for the decoupling of the BBGKY-hierarchy the assumption of vanishing three-particle correlations g₁₂₃ = 0. This yields non-Markovian kinetic equations with infinite memory depth. We discuss a different closure relation to the hierarchy, which overcomes this difficulty without assumptions on weakening of initial correlations and in fact corresponds to the inclusion of selfenergy effects (beyond Hartree-Fock).