Polarized Fermi gases at finite temperature in the BCS-BEC crossover

TL;DR

This paper investigates polarized Fermi gases in the BCS-BEC crossover at finite temperatures using a T matrix approach, addressing previous methodological issues and analyzing phase behavior and physical properties.

Contribution

It introduces a self-consistent treatment of quasiparticle energy shifts that corrects prior approaches in polarized systems.

Findings

Corrected the sign of polarization and spin polarizability.

Computed momentum distributions satisfying Luttinger's theorem at zero temperature.

Discussed phase diagram, spin susceptibility, and compressibility.

Abstract

We consider a polarized Fermi gas in the BCS-BEC crossover region above the critical temperature within a T matrix formalism. By treating the mean-field like shift of the quasiparticle energies in a self-consistent manner, we avoid the known pathological behavior of the standard Nozieres-Schmitt-Rink approach in the polarized case, i.e., the polarization has the right sign and the spin polarizability is positive. The momentum distributions of the correlated system are computed and it is shown that, in the zero-temperature limit, they satisfy the Luttinger theorem. Results for the phase diagram, the spin susceptibility, and the compressibility are discussed.