Pairing fluctuation effects on the single-particle spectra for the superconducting state

TL;DR

This paper investigates how pairing fluctuations influence the single-particle spectra in superconductors across different coupling strengths, bridging BCS and Bose-Einstein regimes, with results aligning well with experimental cuprate data.

Contribution

It introduces a unified theoretical framework that incorporates pairing-fluctuation effects in the superconducting state, valid from weak to strong coupling regimes.

Findings

Spectral functions match experimental cuprate data.

Theory reduces to BCS and Bogoliubov limits in respective regimes.

Provides insights into the evolution of single-particle spectra across coupling strengths.

Abstract

Single-particle spectra are calculated in the superconducting state for a fermionic system with an attractive interaction, as functions of temperature and coupling strength from weak to strong. The fermionic system is described by a single-particle self-energy that includes pairing-fluctuation effects in the superconducting state. The theory reduces to the ordinary BCS approximation in weak coupling and to the Bogoliubov approximation for the composite bosons in strong coupling. Several features of the single-particle spectral function are shown to compare favorably with experimental data for cuprate superconductors.