Unitary Fermi gas at finite temperature in the epsilon expansion

TL;DR

This paper investigates the thermodynamics of the unitary Fermi gas at finite temperature using an epsilon expansion, revealing dominant bosonic excitations at low temperatures and analyzing phase transition properties.

Contribution

It provides analytic formulas for thermodynamic functions at finite temperature and determines the critical temperature for superfluid transition using epsilon expansion.

Findings

Bosonic excitations dominate at low T<<Tc

Analytic thermodynamic functions derived in epsilon expansion

Critical temperature Tc estimated with leading and next-to-leading order corrections

Abstract

Thermodynamics of the unitary Fermi gas at finite temperature is investigated from the perspective of the expansion over epsilon=4-d with d being the dimensionality of space. We show that the thermodynamics is dominated by bosonic excitations in the low temperature region T<<Tc. Analytic formulas for the thermodynamic functions as functions of the temperature are derived to the lowest order in epsilon in this region. In the high temperature region where T Tc, bosonic and fermionic quasiparticles are excited. We determine the critical temperature Tc of the superfluid phase transition and the thermodynamic functions around Tc to the leading and next-to-leading orders in epsilon.