THEORY FOR THE EXCITATION SPECTRUM OF HIGH-T-C SUPERCONDUCTORS - QUASI-PARTICLE DISPERSION AND SHADOWS OF THE FERMI-SURFACE

Using a new method for the solution of the fluctuation exchange approximation equations, which allows the determination of the self-energy Sigma(k)(omega) of the 2D one-band Hubbard model on the real frequency axis, we calculate the doping dependence of the quasiparticle excitations of high-T-c superconductors. We obtain new results for the shadows of the Fermi surface, their dependence on the deformation of the quasiparticle dispersion, an anomalous omega dependence of Im Sigma(k)(omega), and a related violation of the Luttinger theorem. This sheds new light on the influence of short range magnetic order on the low energy excitations and its significance for photoemission experiments.