Exact results for the Anderson model in the limit of zero-width conduction band

Abstract A new method for solving the Anderson model is proposed. The method is based on a perturbation expansion in the kinetic energy of the conduction electrons. In the limit of zero width the model is exactly solvable. By means of the path integral formalism exact analytic expressions for the n-point Green's functions at finite temperature are derived. The analysis is also extended to the case of time-dependent situations by means of Thermo Field Dynamics. A new diagram method to compute the n-point functions is also proposed.