Excitation spectrum of the two-dimensional attractive Hubbard model

TL;DR

This paper investigates the excitation spectrum of the 2D attractive Hubbard model above the superconducting transition, revealing a temperature-independent peak separation and sharpening spectral features near Tc.

Contribution

It introduces a functional integral approach combined with a time-dependent Ginzburg-Landau equation to analyze pair fluctuation effects on spectral functions.

Findings

Double-peak structure around the Fermi wavenumber

Peak separation remains temperature-independent

Spectral features sharpen as temperature approaches Tc

Abstract

We calculate the one-particle spectral functions above the superconducting transition temperature $T_{C}$, in the framework of a functional integral approach. The coupling of the electronic self-energy to pair fluctuations, which are treated by means of a time-dependent Ginzburg-Landau equation, yields a double-peak structure, around the Fermi wavenumber. The peak separation is essentially temperature-independent, but the structure sharpens when $T_{C}$ is approached.