ABSTRACT
Disorder, commonly encountered in the form of random potential scatterers in the metallic host, introduces an additional time scale— the mean free time between successive collisions. Elastic scattering of electrons from such defects can change the momentum but not the energy of the scattering particle. In the leading order in the perturbative expansion, the self energy is purely real. This does not affect the lifetime of the quasiparticle. The vanishing of the quasiparticle decay rate faster than the quasiparticle energy underpins the validity of the Landau Fermi liquid theory. Since interparticle collisions are essential to relax the quasiparticle, the effect of electron-electron interactions on the lifetime appears at higher orders in the perturbation expansion.
