Lattice B-parameters for $\hat{I}”S=2$ and $\hat{I}”I=3/2$ Operators

Abstract

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 ${\hat{I}}^2=6.0$. The renormalization constants and mixing coefficients of the lattice operators have been obtained non-perturbatively. In the $\MSbar$ renormalization scheme, at a renormalization scale $\hat{I}¼\simeq 2$ 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 $\hat{I}{\mu }^{\prime }/\hat{I}\mu$.

LaTeX, 14 pages, revised version (sign misprint in eq. (21) corrected)