Enhancement of anisotropic electron-phonon coupling in the cuprates

Using quantum Monte Carlo techniques, we study the effects of electronic correlations on the electron-phonon coupling in a two-dimensional t-t'-U Hubbard model. We consider a momentum-dependent bare electron-phonon coupling, i.e., the electronic coupling to the B1g oxygen bond-buckling phonon. We find that the on-site Coulomb interaction U acts to effectively enhance the electron-phonon coupling at all electron- and phonon-momenta. Our numerical simulations are in good agreement with the results of functional renormalization group calculations. On the other hand, the forward scattering process near the anti-node is enhanced more than near the nodal region, leading to an enhancement of anisotropic electron-phonon coupling. Our results support the interpretation of the bosonic renormalization effects seen in angle resolved photoemission spectroscopy as electronic coupling to the B1g oxygen bond-buckling phonon