Renormalization flow and universality for ultracold fermionic atoms

S. Diehl, H. Gies, J. M. Pawlowski, C. Wetterich
2007 Physical Review A. Atomic, Molecular, and Optical Physics  
A functional renormalisation group study for the BEC-BCS crossover for ultracold gases of fermionic atoms is presented. We discuss the fixed point which is at the origin of universality for broad Feshbach resonances. All macroscopic quantities depend only on one relevant parameter, the concentration a k_F, besides their dependence on the temperature in units of the Fermi energy. In particular, we compute the universal ratio between molecular and atomic scattering length in vacuum. We also
more » ... t an estimate to which level of accuracy universality holds for gases of Li and K atoms.
doi:10.1103/physreva.76.053627 fatcat:g7nxgj3ocfditfuwcia4sryxki