Fermi-liquid properties of a two-dimensional electron system with the Fermi level near a van Hove singularity

We use a diagrammatic approach to study low-energy physics of a two-dimensi onal electron system where the Fermi level is near van Hove singularities i n the energy spectrum. We find that in most regions of the epsilon(F)-T pha se diagram the system behaves as a normal Fermi liquid rather than a margin al Fermi liquid. Particularly, the imaginary part of the self-energy is muc h smaller than the excitation energy, which implies well-defined quasiparti cle excitations, and single-particle properties are only weakly affected by the presence of the van Hove singularities. The relevance to high-temperat ure superconductivity is also discussed. [S0163-1829(99)11921-0].