Lattice B-parameters for Delta S=2 and Delta I=3/2 operators

We compute several matrix elements of dimension-six four-fermion operators and extract their B-parameters. The calculations have been performed with the tree-level Clover action at beta = 6.0. The renormalization constants and mixing coefficients of the lattice operators have been obtained non-perturbatively. In the <(MS)over bar> renormalization scheme, at a renormalization scale mu similar or equal to 2 GeV, we find B-K(B-9(3/2))=0.66(11), B-7(3/2)=0.72(5) and B-8(3/2)=1.03(3). The result for B-8(3/2) has important implications for the calculation of epsilon'/epsilon. (C) 1998 Elsevier Science B.V.