Spectral function of Fermi polarons at finite temperature from a self-consistent many-body $T$-matrix approach in real frequency

TL;DR

This paper develops a self-consistent many-body T-matrix approach to analyze the finite-temperature spectral function of Fermi polarons, showing improved agreement with experimental spectroscopic data over previous non-self-consistent methods.

Contribution

It introduces a self-consistent T-matrix method in real frequency for Fermi polarons, providing more accurate predictions of spectral functions and spectra at finite temperature.

Findings

Self-consistent approach alters dynamical quantities significantly.

Better matches with recent spectroscopic measurements.

Highlights need for more precise theoretical models.

Abstract

We theoretically examine the finite-temperature spectral function of Fermi polarons in three dimensions, by using a self-consistent many-body $T$-matrix theory in real frequency. In comparison with the previous results from a non-self-consistent many-body $T$-matrix approach, we show that the treatment of self-consistency in the impurity Green function leads to notable changes in almost all the dynamical quantities, including the vertex function, impurity self-energy and spectral function. Eventually, it gives rise to quantitatively different predictions for the measurable radio-frequency spectrum and Raman spectrum at finite temperature. Using the recent spectroscopic measurements as a benchmark, we find that the self-consistent many-body $T$-matrix theory somehow provides a better explanation for the experimental data. The notable difference in the predictions from the non-self-consistent and self-consistent theories suggests that more accurate theoretical descriptions are needed, in order to fully account for the current spectroscopic observations on Fermi polarons.