dx2-y2 symmetry and the pairing mechanism

An important question is, if the gap in the high-temperature cuprates has dx2-y2 symmetry, what does that tell us about the underlying interaction responsible for pairing? Here we explore this by determining how three different types of electron-phonon interactions affect the dx2-y2 pairing found within a random phase approximation treatment of the two-dimensional Hubbard model. These results imply that interactions which become more positive as the momentum transfer increases favor dx2-y2 pairing in a nearly half-filled band. copyright 1996 The American Physical Society