Fermi surface and gap parameter in high-T-c superconductors: the Stripe Quantum Critical Point scenario

We study the single-particle spectral properties of electrons coupled to qu asicritical charge and spin fluctuations close to a stripe-phase, which is governed by a Quantum Critical Point near optimum doping. We find that spec tral weight is transferred from the quasiparticle peak to incoherent disper sive features. As a consequence, the distribution of low-laying spectral we ight is modified with respect to the quasiparticle Fermi surface. The inter play of charge and spin fluctuations reproduces features of the observed Fe rmi surface, such as the asymmetric suppression of spectral weight near the M points of the Brillouin zone. Within the model, we also analyze the inte rplay between repulsive spin and attractive charge fluctuations in determin ing the symmetry and the peculiar momentum dependence of the superconductin g gap parameter. When both spin and charge fluctuations are coupled to the electrons, we find d(x2-y2)-wave gap symmetry in a wide range of parameter. A crossover d- vs. s-wave symmetry of the gap may occur when the strength of charge fluctuations increases with respect to spin fluctuations. (C) 199 9 Published by Elsevier Science B.V. All rights reserved.