Electron-electron correlation through electron-plasmon coupling in high-T c superconductors

A model for high T c superconductivity is considered. The Cu d x 2 - y 2 electrons correlate by means of polarization-plasmon interaction. We show that when the plasmon energy approaches to the energy difference of the two bands of Cu d x 2 - y 2 a resonant-enhanced interaction between the electrons can be realized. In this model the oxygen vacancies are responsible for the high-Tc superconductivity to which the plasmon frequency is mainly related.