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 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.
B-parameters for ΔS=2 supersymmetric operators
We present a calculation of the matrix elements of the most general set of DeltaS=2 dimension-six four-fermion operators. The values of the matrix elements are given in terms of the corresponding B-parameters. Our results can be used in many phenomenological applications, since the operators considered here give important contributions to K^0--K^0bar mixing in several extensions of the Standard Model (supersymmetry, left-right symmetric models, multi-Higgs models etc.). The determination of the matrix elements improves the accuracy of the phenomenological analyses intended to put bounds on basic parameters of the different models, as for example the pattern of the sfermion mass matrices. Th…