Normal-state properties of a unitary Bose–Fermi mixture: A combined strong-coupling approach with universal thermodynamics

We theoretically investigate normal-state properties of a unitary Bose–Fermi mixture. Including strong hetero-pairing fluctuations, we evaluate the Bose and Fermi chemical potential, internal energy, pressure, entropy, as well as specific heat at constant volume C_V, within the framework of a combined strong-coupling theory with exact thermodynamic identities. We show that hetero-pairing fluctuations at the unitarity cause non-monotonic temperature dependence of C_V, being qualitatively different from the monotonic behavior of this quantity in the weak- and strong-coupling limit. On the other hand, such an anomalous behavior is not seen in the other quantities. Our results indicate that the specific heat C_V, which has recently become observable in cold atom physics, is a useful quantity for understanding strong-coupling aspects of this quantum system.