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

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's 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.