Comparing lattice Dirac operators in smooth instanton backgrounds

We compare the behavior of different lattice Dirac operators in gauge backg rounds which are lattice discretizations of a classical instanton. In parti cular, we analyze the standard Wilson operator, a chirally improved Dirac o perator and the overlap operators constructed from these two operators. We discuss the flow of real eigenvalues as a function of tile instanton size. An analysis of the eigenvectors shows that overlap fern-Lions with the Wils on operator as input operator have difficulties with reproducing the contin uum zero mode already for moderately small instantons. This problem is grea tly reduced when using the chirally improved operator for the overlap proje ction. (C) 2001 Elsevier Science B.V. All rights reserved.