Reducing Residual-Mass Effects for Domain-Wall Fermions

It has been suggested to project out a number of low-lying eigenvalues of the fourdimensional Wilson–Dirac operator that generates the transfer matrix of domain-wall fermions in order to improve simulations with domain-wall fermions. We investigate how this projection method reduces the residual chiral symmetry-breaking effects for a finite extent of the extra dimension. We use the standardWilson as well as the renormalization– group–improved gauge action. In both cases we find a substantially reduced residual mass when the projection method is employed. In addition, the large fluctuations in this quantity disappear.