What does d-wave symmetry tell us about the pairing mechanism?

In this paper we argue that d-wave symmetry is a general consequence of superconductivity driven by repulsive interactions. Van Hove (or flat band) effects, deriving from the two dimensionality of the $CuO_2$ plane are important in stabilizing this state. By extending the original Kohn-Luttinger picture to a 2 D lattice, we find that the screened Coulomb term has important wave vector structure which leads to $d_{x^2-y^2}$ superconductivity