Gossamer supercoductivity and the mean field approximation of a new   effective Hubbard model
  We construct a new effective two-dimensional Hubbard model by taking the different electron occupancy on site into account. The mean field state of the new Hamiltonian gives rise to the gossamer superconducting state proposed by Laughlin recently(cond-mat/0209269). 
Yue Yu (ITP, Beijing)