Numerical reinvestigation of the Aoki phase with N_{f}=2 Wilson fermions at zero temperature

Abstract

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 hψ̅ iγ5τ3ψ was added to the fermion action. The order parameter 〈ψ̅ iγ5τ3ψ〉 was computed with the hybrid Monte Carlo algorithm at several values of (β,κ,h) on lattices of sizes 44 to 124 and extrapolated to h=0. The existence of a parity-flavor breaking phase can be confirmed at β=4.0 and 4.3, while we do not find parity-flavor breaking at β=4.6 and 5.0.