We investigate a model for the CuO_2 plane of high-T_c superconductors wherethe charge carriers are coupled to A_{1g} and B_{1g} symmetric out-of planevibrations of the oxygen atoms in the presence of local Hubbard correlations.The coupling is implemented via a modulation of the hopping integral and wecalculate the renormalization of vertex and pairing scattering functions basedon the time-dependent Gutziller approximation. Contrary to localelectron-phonon couplings we find that the transitive coupling can even beenhanced by correlations for certain momenta and symmetries of the vibrations.While this effect may be important for certain properties, we find that, withregard to superconductivity, electron-electron correlations still genericallylead to a suppression of the pairing correlations. Our results allow for anestimate of correlation effects on the electron-phonon induced pair scatteringfrom weak electron-electron interactions up to the Mott regime. For onsiterepulsions relevant to cuprate superconductors our calculations reveal asignificant contribution of B_{1g} phonons to d-wave superconductivity.
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