NONANALYTIC CONTRIBUTIONS TO THE SELF-ENERGY AND THE THERMODYNAMICS OF 2-DIMENSIONAL FERMI LIQUIDS

We calculate the entropy of a two-dimensional Fermi liquid using a model with a contact interaction between fermions. We find that there are T2 contributions to the entropy from interactions separate from those due to the collective modes. These T2 contributions arise from nonanalytic corrections to the real part of the self-energy which may be calculated from the leading-log dependence of the imaginary part of the self-energy through the Kramers-Kronig relation. We find no evidence of a breakdown in Fermi liquid theory in 2D and conclude that Ferrmi liquids in 2D are similar to 3D Fermi liquids.