NONPERTURBATIVE IMPROVEMENT OF COMPOSITE-OPERATORS WITH WILSON FERMIONS

We propose a method to improve lattice operators composed of Wilson fe rmions which allows the removal of all corrections of O(a), including those proportional to the quark mass, leaving only errors of O(a(2)). The method exploits the fact that chiral symmetry is restored at short distances. By imposing this requirement on correlation functions of i mproved lattice operators at short distances, the coefficients which a ppear in these operators can be determined. The method is an extension of the improvement program of the Alpha collaboration, which, up to n ow, has only been applicable in the chiral limit. The extension to qua rks with non-zero masses is particularly important for applications in heavy quark physics. (C) 1997 Elsevier Science B.V.