Landau quasiparticles are long-lived excitations with a lifetime τ τ that satisfies ℏ ℏ τ τ ≪ ≪ ϵ ϵ p where ϵ ϵ p is the quasiparticle energy (measured from the Fermi energy). At finite temperature, ϵ ϵ p is on the order of the thermal energy k B T , and the condition for Landau quasiparticles can be reformulated as ℏ ℏ τ τ ≪ ≪ k B T .