The Kaon B-parameter and K-π and K-ππ transition amplitudes on the lattice

We present the results of a computation of the K0-K0 and ΔI = 3 2 K-π and K-ππ amplitudes in lattice QCD. The numerical simulation has been done using the standard one-plaquette action and Wilson fermions, in the quenched approximation. Combining the tesults obtained at β = 6 on a 102 × 20 × 40 lattice with 30 configurations with those at β = 6.2 on a 163 × 48 lattice with 15 configurations, we have obtained for the kaon B-parameterBKjavax.xml.bind.JAXBElement@6ce04442 - Kjavax.xml.bind.JAXBElement@7f4f25ff = 0.65 ± 0.15 at μ = 3 GeV. We have also evaluated the ΔI = 3 2K-π and K-π weak hamiltonian matrix elements. The relevant renormalized operator O4 has been found to satisfy soft-pion theorems and chiral lagrangian relations at the 30% level, and this makes us confident about our results. We find (〈K+|HW|π+π0 〉/mK) = (7 ± 2) × 10-8 to be compared with the experimental value of 3.7 × 10-8. © 1988.