Bound states of fermions on 2D lattice in a dilute limit

We examine extended bound states in a dilute Limit of the extended Hubbard model on the two-dimensional square lattice. By solving exactly the two-bod y problem we have determined the binding energies, mobilities, and dispersi on curves across the Brillouin zone for bound states of various symmetries. It turns out that the d-wave pairing is strongly favored by the nnn hoppin g and the intersite local pairs can have small effective masses, even in th e case of strong binding. We have also found a possibility of extended s-d( x2-y2) mixing of the bound states.