Hartree shift in unitary Fermi gases
  The Hartree energy shift is calculated for a unitary Fermi gas. By including the momentum dependence of the scattering amplitude explicitly, the Hartree energy shift remains finite even at unitarity. Extending the theory also for spin-imbalanced systems allows calculation of polaron properties. The results are in good agreement with more involved theories and experiments. 
J. J. Kinnunen
cond-mat.quant-gas cond-mat.str-el quant-ph