Ground State of a trapped Bose-Einstein Condensate in Two Dimensions;   Beyond the Mean-field Approximation
  We consider the ground state of a trapped Bose-Einstein condensate in two dimensions. In the mean-field approximation, the ground state density profile satisfies the Gross-Pitaevskii equation. We compute the leading quantum corrections to the density profile to second order in an expansion around the Thomas-Fermi limit. By summing the ladder diagrams, we are generalizing Schick's result for the ground state energy of a homogeneouns Bose gas to the case of a trapped Bose gas. 
Jens O. Andersen and Haarek Haugerud