Phonon contribution to high-Tc superconductivity: Tunneling conductance and photoelectron dispersion relation

Quasi-particle dispersion relations were calculated within the Migdal approximation for the tunneling spectral function of the electron–phonon interaction obtained by us in slightly overdoped Bi2Sr2CaCu2O8. These relations were compared with the photoelectron results by Gweon et al. If a linear dispersion relation is assumed for a bare state, considerable discrepancies are observed. However, many similarities are noted with regard to local changes in the dispersion relations such as a kink, a discontinuity at the maximum phonon frequency, and an isotope shift in a single-phonon frequency range.