Weakly Interacting Bose-Einstein Condensates Under Rotation: Mean-field   versus Exact Solutions
  We consider a weakly-interacting, harmonically-trapped Bose-Einstein condensed gas under rotation and investigate the connection between the energies obtained from mean-field calculations and from exact diagonalizations in a subspace of degenerate states. From the latter we derive an approximation scheme valid in the thermodynamic limit of many particles. Mean-field results are shown to emerge as the correct leading-order approximation to exact calculations in the same subspace. 
A. D. Jackson (Niels Bohr Institute, Denmark), G. M. Kavoulakis   (NORDITA, Denmark), B. Mottelson (NORDITA, Denmark), and S...