Charge-Density-Wave Pseudogap and Two-Dimensional Superconductivity Within Strong-Coupling Description

We have considered the role of charge-density-pseudogap for phonon-mediated super-conductivity on two-dimensional lattice. The propagators that enter generalized Eliashberg equations have been renormalized to account for quasi-particle energies related to the formation of the pseudogap, which has been assumed to be of d-wave symmetry. We have evaluated the superconducting transition temperature Tc as a function of doping. It occurs that Tc for d-wave symmetry well reflects experimental behavior. Our results for the isotope shift exponent α show that at low doping, the presence of the pseudogap may contribute to α > 1/2 as well as to α > 1/2 values.