Equilibrium and non-equilibrium dynamics of quasiparticles for locally correlated systems in a magnetic field

We present renormalised perturbation theory calculations for the description of the dynamics of quasiparticles in the Anderson impurity model in magnetic field. Our calculations are compared with NRG spectra and good agreement is found for magnetic fields of the order of the Kondo temperature, when an appropriate perturbation series is chosen. We point out how this approach can be generalised to the non-equilibrium situation, where it is relevant for the description of quantum dots. (c) 2006 Elsevier B.V. All rights reserved.