Pairing and the spin susceptibility of the polarized unitary Fermi gas in the normal phase

TL;DR

This paper investigates the pairing behavior and spin susceptibility of the polarized unitary Fermi gas in the normal phase using complex Langevin and virial expansion methods, providing insights into its phase diagram.

Contribution

It introduces a combined theoretical approach using complex Langevin and virial expansion to analyze spin susceptibility in polarized Fermi gases, expanding understanding of their phase behavior.

Findings

Calculated spin susceptibility using complex Langevin approach.

Extended analysis to polarized systems with high-temperature virial expansion.

Discussed implications for the phase diagram of spin-polarized Fermi gases.

Abstract

We theoretically study the pairing behavior of the unitary Fermi gas in the normal phase. Our analysis is based on the static spin susceptibility, which characterizes the response to an external magnetic field. We obtain this quantity by means of the complex Langevin approach and compare our calculations to available literature data in the spin-balanced case. Furthermore, we present results for polarized systems, where we complement and expand our analysis at high temperature with high-order virial expansion results. The implications of our findings for the phase diagram of the spin-polarized unitary Fermi gas are discussed, in the context of the state of the art.