A study of 'improvement' in lattice QCD

We perform a numerical simulation in quenched lattice QCD using an improved action for the quarks. With this action, the systematic errors in hadronic matrix elements due to the finiteness of the lattice spacing are reduced from terms of O(a) to ones of O(go2a), where a and g0 are the lattice spacing and bare coupling constant, respectively. We demonstrate explicitly that for matrix elements of the vector current this corresponds to a reduction of these errors from about 20-30% to about 5%. We therefore propose that future simulations in lattice QCD be performed using an improved fermion action. (orig.)