Unconventional Quasiparticle Lifetime in Graphite

The influence of electron-electron scattering on quasiparticle lifetimes in graphite is calculated. In the limit when the Fermi surface is reduced to isolated points in the Brillouin zone, the suppression of screening leads to deviations from conventional Fermi liquid behavior. The inverse lifetime increases linearly with energy, in agreement with recent experiments. Similar features should also be present in narrow gap semiconductors and in carbon nanotubes.