Feshbach-resonant interactions in 40K and 6Li degenerate Fermi gases -: art. no. 060403

We theoretically examine a system of Fermi degenerate atoms coupled to bosonic molecules by a Feshbach resonance, focusing on the superfluid transition to a molecular Bose-Einstein condensate dressed by Cooper pairs of atoms. This problem raises interest because it is unclear at present whether bimodal density distributions observed recently in K-40 and Li-6 are due to a condensate of bosonic molecules or fermionic atom pairs. As opposed to K-40, we find that any measurable fraction of above-threshold bosonic molecules is necessarily absent for the Li-6 system in question, which strongly implicates Cooper pairs as the culprit behind its bimodal distributions.