Proximity of the Superconducting Dome and the Quantum Critical Point in the Two-Dimensional Hubbard Model

We use the dynamical cluster approximation to understand the proximity of the superconducting dome to the quantum critical point in the two-dimensional Hubbard model. In a BCS formalism, $T_c$ may be enhanced through an increase in the d-wave pairing interaction ($V_d$) or the bare pairing susceptibility (${\chi }_{0d}$). At optimal doping, where $V_d$ is revealed to be featureless, we find a power-law behavior of ${\chi }_{0d}(\omega =0)$, replacing the BCS log, and strongly enhanced $T_c$. We suggest experiments to verify our predictions.