Article,
Interacting preformed Cooper pairs in resonant Fermi gases
Physical Review A, 84 (1): 013610+ (July 2011)
DOI: 10.1103/physreva.84.013610
Abstract
We consider the normal phase of a strongly interacting Fermi gas, which can have either an equal or an unequal number of atoms in its two accessible spin states. Due to the unitarity-limited attractive interaction between particles with different spin, noncondensed Cooper pairs are formed. The starting point in treating preformed pairs is the Nozières-Schmitt-Rink (NSR) theory, which approximates the pairs as being noninteracting. Here, we consider the effects of the interactions between the Cooper pairs in a Wilsonian renormalization-group scheme. Starting from the exact bosonic action for the pairs, we calculate the Cooper-pair self-energy by combining the NSR formalism with the Wilsonian approach. We compare our findings with the recent experiments by Harikoshi et al. Science 327 442 (2010) and Nascimbène et al. Nature (London) 463 1057 (2010), and find very good agreement. We also make predictions for the population-imbalanced case, which can be tested in experiments.
