NONPERTURBATIVE RENORMALIZATION OF THE LATTICE DELTA-S=2 4-FERMION OPERATOR

We compute the renormalised four-fermion operator O-Delta S=2 using a non-perturbative method recently introduced for determining the renormalisation constants of generic lattice composite operators. Because of the presence of the Wilson term, O-Delta S=2 mixes with operators of different chiralities, A projection method to determine the mixing coefficients is implemented, The numerical results for the renormalisation constants have been obtained from a simulation performed using the SW-Clover quark action, on a 16(3) x 32 lattice, at beta = 6.0. We show that the use of the constants determined non-perturbatively improves the chiral behaviour of the lattice kaon matrix element [(K) over bar(0)\O-Delta S=2\K-0]latt.