Spectral Properties of the Attractive Hubbard Model

TL;DR

This paper studies the spectral properties of the attractive Hubbard model using a self-consistent ladder approximation, revealing differences from non-self-consistent theories and implications for understanding high-temperature superconductors.

Contribution

It provides a self-consistent analysis of the attractive Hubbard model, highlighting how interactions alter superconducting instability and spectral features compared to previous non-self-consistent approaches.

Findings

No pseudo-gap features are present in the self-consistent theory.

Interactions between bound states significantly modify superconducting behavior.

The phenomenology differs markedly from non-self-consistent predictions.

Abstract

Deviations from Fermi liquid behavior are well documented in the normal state of the cuprate superconductors, and some of these differences are possibly related to pre-formed pairs appearing at temperatures above T_c. In order to test these ideas we have investigated the attractive Hubbard model within a self-consistent, conserving ladder approximation. In this version of the theory, no feature is present which can be related to the pseudo gap found in the high-T_c materials. Further, the interactions between two-particle bound states change the physics of the superconducting instability in a profound fashion, and lead to a completely different phenomenology that one predicts based on the non-self-consistent version of the same theory.