Boson approximations for localized dynamic perturbations in metals

Abstract

Recently we proposed two boson approximations to describe the creation of electronhole—pair excitations by a localized time-dependent perturbation. These boson approximations were shown to be exact in certain limiting cases. In this paper we compare the results in these approximations with exact calculations where the electrons are treated as fermions. We show that the validity of the approximations is broader than had earlier been proven.