PLASMARON EXCITATION AND BAND RENORMALIZATION IN A 2-DIMENSIONAL ELECTRON-GAS

The structure of a plasmaron excitation is described for a two-dimensional electron gas at T = 0 K. It is shown to lead to a staircaselike density of states with three steps. The band renormalization is then calculated by taking the imaginary part of the self-energy fully into account. The renormalization of the chemical potential is shown to be smaller than that of the edge of the density of states. The quasiparticle energy dispersion is strongly nonparabolic but the renormalization of the effective mass at the Fermi surface is found to be well approximated by the widely used lowest-order approximation.