Pairing Mechanism in the Two-Dimensional Hubbard Model

Here we discuss Quantum Monte Carlo results for the magnetic susceptibility, single-particle spectral weight and the irreducible particle-particle interaction vertex of the two-dimensional Hubbard model. In the doped system, as the temperature is lowered below J=4t^2/U, short-range antiferromagnetic correlations develop. These lead to a narrow low-energy quasiparticle band with a large Fermi surface and a particle-particle vertex which increases at large momentum transfer, which favor d_{x^2-y^2}-pairing.