Effects of strong Coulomb correlations on the phonon-mediated superconductivity: A model inspired by Copper oxides

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Abstract
We study how strong Coulomb correlations affect the phonon-mediated superconductivity. Using the Hubbard model representation of a strongly correlated system, we evaluate the Eliashberg electron-pair correlation function for different values of hole doping concentration, x. The pair interaction is repulsive near half filling (x=0), but it becomes attractive above some critical value of x, making the phonon-mediated superconductivity possible. We also compute the isotope effect coefficient.