Fermi Liquid Theory

Physics: Landau Fermi liquid: electron-electron interactions renormalize quasiparticle properties but do not destroy the Fermi surface. Effective mass m* = m(1 + F₁ˢ/3) where F₁ˢ is a Landau parameter; specific heat C/T = γ = (π²/3)k_B² g(E_F) ∝ m*. Fermi energy E_F = ℏ²(3π²n)^(2/3)/2m, T_F ≈ 50,000 K for metals. Non-Fermi liquids (NFL) appear near quantum critical points: C/T ~ −ln(T), ρ ~ T^(3/2) instead of T². Quasiparticle lifetime τ ~ (E−E_F)^(−2), so states far from E_F decay quickly; near E_F they become arbitrarily long-lived — the basis of FL theory.