Evidence for d-wave superconductivity in the repulsive Hubbard-model
  We perform numerical simulations of the Hubbard model using the projector Quantum Monte Carlo method. A novel approach for finite size scaling is discussed. We obtain evidence in favor of d-wave superconductivity in the repulsive Hubbard model. For U=4, $T_c$ is roughly estimated as $T_c\approx 30K$. 
W. Fettes and I. Morgenstern