Feshbach-Resonant Interactions in $^{40}$K and $^6$Li Degenerate Fermi Gases

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 an interest because it is unclear at present whether bimodal density distributions observed recently in $^{40}$K and $^6$Li are due to a condensate of bosonic molecules or fermionic atom pairs. As opposed to $^{40}$K, we find that any measurable fraction of above-threshold bosonic molecules are necessarily absent for the $^6$Li system in question, which strongly implicates Cooper pairs as the culprit behind its bimodal distributions.