Comparison between theory and experiment for universal thermodynamics of a homogeneous, strongly correlated Fermi gas

We compare the theoretical predictions for universal thermodynamics of a homogeneous, strongly correlated Fermi gas with the latest experimental measurements reported by the ENS group [S. Nascimbène et al., Nature (London) 463, 1057 (2010)] and the Tokyo group [M. Horikoshi et al., Science 327, 442 (2010)]. The theoretical results are obtained using two diagrammatic theories, together with a virial expansion theory combined with a Páde approximation. We find good agreement between theory and experiment. In particular, the virial expansion, using a Páde approximation up to third order, describes the experimental results extremely well down to the superfluid transition temperature, Tc~0.16TF, where TF is the Fermi temperature. The comparison in this work complements our previous comparative study on the universal thermodynamics of a strongly correlated but trapped Fermi gas. The comparison also raises interesting issues about the unitary entropy and the applicability of the Páde approximation.