Superconducting transition as a two-dimensional Kosterlitz-Thouless transition evidenced by quantum Monte Carlo calculations of susceptibilities in two-dimensional Hubbard model

We investigate the superconducting transition in two space dimensions as a Kosterlitz-Thouless transition on the basis of quantum Monte Carlo computations of pair susceptibilities in the two-dimensional Hubbard model. We use the auxiliary quantum Monte Carlo method to calculate the pair susceptibility in the ground state. The numerical results show that the s-wave pair susceptibility scales as chi(s)(pair) similar to L(2) for the attractive case, in agreement with previous quantum Monte Carlo studies. We show that the scaling chi(d)(pair) similar to L(2) also holds for the d-wave pair susceptibility for the repulsive Hubbard model if we adjust the band parameter t'. (C) 2010 Published by Elsevier B.V.