Correlations and Pair Formation in a Repulsively Interacting Fermi Gas
  A degenerate Fermi gas is rapidly quenched into the regime of strong effective repulsion near a Feshbach resonance. The spin fluctuations are monitored using speckle imaging and, contrary to several theoretical predictions, the samples remain in the paramagnetic phase for arbitrarily large scattering length. Over a wide range of interaction strengths a rapid decay into bound pairs is observed over times on the order of 10\hbar/E_F, preventing the study of equilibrium phases of strongly repulsive fermions. Our work suggests that a Fermi gas with strong short-range repulsive interactions does not undergo a ferromagnetic phase transition. 
Christian Sanner, Edward J. Su, Wujie Huang, Aviv Keshet, Jonathon   Gillen, Wolfgang Ketterle
cond-mat.quant-gas physics.atom-ph