Quasiparticle excitations and dynamic susceptibilities in the BCS-BEC crossover

TL;DR

This paper investigates the evolution of quasiparticle excitations and susceptibilities across the BCS-BEC superfluid crossover using an advanced DMFT-NRG approach, revealing suppression of quasiparticles and providing insights into spectral and gap properties.

Contribution

It introduces an extension of the NRG method for selfconsistent superconducting calculations within the DMFT framework, enabling detailed study of the BCS-BEC crossover.

Findings

Quasiparticle spectra show suppression at intermediate coupling.

Results include detailed spin and charge gap behaviors.

Demonstrates the applicability of the extended NRG method for superconducting systems.

Abstract

We study dynamic ground state properties in the crossover from weak (BCS) to strong coupling (BEC) superfluidity. Our approach is based on the attractive Hubbard model which is analyzed by the dynamical mean field theory (DMFT) combined with the numerical renormalization group (NRG). We present an extension of the NRG method for effective impurity models to selfconsistent calculations with superconducting symmetry breaking. In the one particle spectra we show quantitatively how the Bogoliubov quasiparticles at weak coupling become suppressed at intermediate coupling. We also present results for the spin and charge gap. The extension of the NRG method to selfconsistent superconducting solutions opens the possibility to study a range of other important applications.