Singularity in the quasiparticle interaction function in a 2D Fermi gas
Baranov M. A. , Kagan M. Yu. , Mar'enko M. S.
The interaction function of Landau quasiparticles, /(ρ, p'), of a 2D Fermi gas is calculated in second-order perturbation theory. This function has a square-root singularity near the Fermi surface when the momenta ρ and p' are nearly parallel. Although this singularity does not disrupt the Fermi-liquid picture in the 2D case, it does lead to some nontrivial corrections to thermodynamic properties and to the zero sound velocity.