= Low-energy Fermi-liquid quasiparticle lifetime
{title2=$\tau^{-1}\propto(\epsilon-\mu)^2+(\pi k_BT)^2$}
The <Pauli exclusion principle> restricts final states available to a low-energy <Landau quasiparticle> and the particle–<hole> pair it excites. In a regular three-dimensional <Fermi liquid>, this phase-space restriction makes the decay rate quadratic in excitation <energy> or <temperature>. The excitation's width divided by its <energy> therefore vanishes at the <Fermi surface>, allowing an asymptotically sharp quasiparticle despite interactions.
Back to article page
