d-wave superconductivity in the presence of a near neighbor Coulomb repulsion

Dynamic cluster quantum Monte Carlo calculations for a doped two-dimensional extended Hubbard model are used to study the stability and dynamics of $d$-wave pairing when a near neighbor Coulomb repulsion $V$ is present in addition to the on-site Coulomb repulsion $U$. We find that $d$-wave pairing and the superconducting transition temperature $T_c$ are only weakly suppressed as long as $V$ does not exceed $U\mathrm{/}2$. This stability is traced to the strongly retarded nature of pairing that allows the $d$-wave pairs to minimize the repulsive effect of $V$. When $V$ approaches $U\mathrm{/}2$, large momentum charge fluctuations are found to become important and to give rise to a more rapid suppression of $d$-wave pairing and $T_c$ than for smaller $V$.