Fermi liquid theory

Summary

Fermi liquid theory, due to Lev Landau in 1956, describes interacting fermions, such as electrons in a metal or liquid helium-3, at low temperature. Its central claim is that the low-energy excitations are quasiparticles in one-to-one correspondence with the excitations of a free Fermi gas. The quasiparticles have a renormalised mass and interact through a few Landau parameters. It explains why the free-electron picture of metals works so well, with a heat capacity linear in temperature and a sharp Fermi surface.