Numerical reinvestigation of the Aoki phase with Nf=2 Wilson fermions at zero temperature -: art. no. 074511

We report on a numerical reinvestigation of the Aoki phase in lattice QCD with two flavors of Wilson fermions where the parity-flavor symmetry is spontaneously broken. For this purpose an explicitly symmetry-breaking source term h (psi) over barigamma(5)tau(3)psi was added to the fermion action. The order parameter <(psi) over barigamma(5)tau(3)psi> was computed with the hybrid Monte Carlo algorithm at several values of (beta,kappa,h) on lattices of sizes 4(4) to 12(4) and extrapolated to h=0. The existence of a parity-flavor breaking phase can be confirmed at beta=4.0 and 4.3, while we do not find parity-flavor breaking at beta=4.6 and 5.0.