BCS Superfluidity in Ultracold Li-6 Gas

Recent progress toward degeneracy in ultracold Fermi gases raise hope to reach the BCS superfluuid transition in fermionic systems, the case of 6 Li being very favorable in view of its expected large and negative scattering length. We discuss the physical situation in the high density regime where the critical temperature is expected to be large. Indirect interaction due to the exchange of density fluctuations should play an important role. We discuss the physical points involved in our approximate calculation of the critical temperature which retains the same set of diagrams as in the paramagnon model. Near the instability threshold, the attractive interaction due to density fluctuations gives rise to a strong increase in the critical temperature, providing a clear signature of the existence of fluctuation induced interactions.