Fermi Surface of the 2D Hubbard Model at Weak Coupling

TL;DR

This paper investigates how weak interactions deform the Fermi surface in the 2D Hubbard model, revealing enhanced anisotropies without changing the Fermi surface topology.

Contribution

It provides a second order perturbation theory analysis of Fermi surface deformation in the 2D Hubbard model at weak coupling.

Findings

Interactions enhance Fermi surface anisotropy near half-filling

Fermi surface topology remains unchanged in the weak coupling regime

Deformation is quantitatively characterized by second order perturbation theory

Abstract

We calculate the interaction-induced deformation of the Fermi surface in the two-dimensional Hubbard model within second order perturbation theory. Close to half-filling, interactions enhance anisotropies of the Fermi surface, but they never modify the topology of the Fermi surface in the weak coupling regime.