Marginal Fermi liquid behaviour in the d=2 Hubbard model with cut-off

TL;DR

This paper demonstrates that the half-filled 2D Hubbard model with a momentum cut-off exhibits Marginal Fermi liquid behavior, providing insights into non-Fermi liquid phenomena relevant to high-temperature superconductors.

Contribution

It introduces a rigorous Renormalization Group analysis showing Marginal Fermi liquid behavior in a modified Hubbard model with a specific momentum cut-off.

Findings

Proves the system is not a Fermi liquid

Establishes Marginal Fermi liquid behavior at low temperatures

Provides a convergent expansion for the Schwinger function

Abstract

We consider the half-filled Hubbard model with a cut-off forbidding momenta close to the angles of the square shaped Fermi surface. By Renormalization Group methods we find a convergent expansion for the Schwinger function up to exponentially small temperatures. We prove that the system is not a Fermi liquid, but on the contrary it behaves like a Marginal Fermi liquid, a behaviour observed in the normal phase of high T_c superconductors.