Quantum criticality in the 2D Hubbard: from weak to strong coupling

We study the phase diagram of the two-dimensional Hubbard model in the vicinity of the quantum critical point which separates the fermi liquid from the pseudogap region. We use the Dynamical Cluster Approximation (DCA) in conjunction with the weak-coupling continuous time quantum Monte Carlo (CTQMC) cluster solver. We measure the filling $n_c$ and the density of states at the critical point as a function of the Coulomb interaction $U$. We observe a change in behavior when the Coulomb interaction is of the order of the bandwidth. We also evaluate the temperature range in which the system is under the influence of the quantum critical point and compare it with the effective spin coupling $J_{eff}$. We discuss the consistency of these results with various mechanisms of quantum criticality. This research is supported by NSF DMR-0706379 and OISE-0952300.