Momentum-resolved spectroscopy of a Fermi liquid

TL;DR

This paper develops an extended Brueckner-Goldstone theoretical model to analyze momentum-resolved spectroscopy in strongly interacting Fermi gases, revealing quasiparticle behavior and aligning well with experimental results.

Contribution

It introduces a beyond-mean-field theoretical framework for Fermi liquids that accurately describes spectroscopic properties across various regimes.

Findings

The model predicts well-defined quasiparticles in strongly interacting gases.

Qualitative agreement with experimental spectroscopy data.

Insights into pair correlations, Tan's contact, and mean-field effects.

Abstract

We consider a recent momentum-resolved radio-frequency spectroscopy experiment, in which Fermi liquid properties of a strongly interacting atomic Fermi gas were studied. Here we show that by extending the Brueckner-Goldstone model, we can formulate a theory that goes beyond basic mean-field theories and that can be used for studying spectroscopies of dilute atomic gases in the strongly interacting regime. The model hosts well-defined quasiparticles and works across a wide range of temperatures and interaction strengths. The theory provides excellent qualitative agreement with the experiment. Comparing the predictions of the present theory with the mean-field Bardeen-Cooper-Schrieffer theory yields insights into the role of pair correlations, Tan's contact, and the Hartree mean-field energy shift.