Volume independence of large-N QCD with adjoint fermions

It has been proposed that four-dimensional QCD with fermions in the adjoint representation exhibits volume-independence in the large-N limit. If correct, this would mean that results for physical quantities could be obtained from the single-site vers ion of the model. A necessary condition for volume-independence is that the (ZN) 4 center-symmetry of the single-site theory is unbroken. We explore the phase diagram of the theory with a single Dirac fermion using Wilson fermions for a number of colors in the range 8 ≤ N ≤ 15, and identify the region in the parameter space of quark mass and gauge coupling where the symmetry appears to be unbroken. Our evidence suggests that this region includes both light and heavy quar ks, and our results are consistent with this region extending to the continuum limit.