PROPERTIES OF FERMI LIQUIDS WITH A FINITE-RANGE INTERACTION

Following a suggestion of Khodel' and Shaginyan (KS), it is shown that a Hartree Fock description of Fermi liquids can lead to very strange results when the interaction has long range. For instance, the sharp drop of particle distribution at the Fermi level can be smeared over a finite k-range, with a flat plateau in the quasiparticle energy. In practice, such an effect appears as an artefact of the Hartree Fock approximation. The KS effect occurs only for an attraction, in which case it is hidden by superconductivity. Moreover, the enhanced quasiparticle collision rate makes the Hartree Fock approximation untenable. Finally, screening of a strong long range interaction is such that the instability threshold cannot be reached.