Improving the Dirac operator in lattice QCD Original Research Article

Recently various new concepts for the construction of Dirac operators in lattice quantum chromodynamics (QCD) have been introduced. These operators satisfy the so-called Ginsparg–Wilson condition (GWC), thus obeying the Atiyah–Singer index theorem and violating chiral symmetry only in a modest and local form. Here we present studies in 4D for SU(3) gauge configurations with non-trivial topological content. We study the flow of eigenvalues and we compare the numerical stability and efficiency of a recently suggested chirally improved operator with that of others in this respect.