Stripes, pseudogaps, and SO(6) in the cuprate superconductors

We briefly summarize two related calculations. First, we demonstrate that the instabilities (either nesting or pairing) associated with the high-T_c cuprates can be described by an SO(6) transformation group. There are two independent 6-dimensional representations (`superspins'). One superspin combines Zhang's 5-component superspin with a flux phase instability; the other involves a charge density wave, s-wave superconductivity, and an exotic spin current. The second calculation is a self-consistent slave boson calculation, which provides a good description of the doping dependence of the photoemission dispersion in terms of dynamic striped phases. The stripes are stabilized by strong electron-phonon coupling, and provide evidence for a doping-dependent crossover between the two superspin groundstates.