Improving the chiral properties of lattice fermions -: art. no. 054501

The chiral properties of lattice fermions can be improved by altering either their fermion-gauge coupling or the pure gauge part of the action (or both). Using both perturbation theory and nonperturbative simulation, we compare a simple alteration of the gauge action [which encompasses the Wilson, Symanzik, Iwasaki, and doubly blocked from Wilson action in two coupling space (DWB2) actions], and hypercubic-blocked links in the fermion action. Perturbative tests include calculations of the potential, flavor-changing quark scattering amplitudes, and matching factors for currents. Nonperturbative tests include the potential, measurements of flavor symmetry breaking for staggered fermions, the behavior of topological objects, and properties of overlap actions. Our results display the bad properties of these actions as well as their good ones.