K-]PI(+) PI(0) DECAY AMPLITUDE WITH THE WILSON QUARK ACTION IN QUENCHED LATTICE QCD - ART. NO. 054503()

We present a calculation for the K+ --> pi(+) pi(0) decay amplitude us ing a quenched simulation of lattice QCD with the Wilson quark action at beta = 6/g(2) = 6.1. The decay amplitude is extracted from the rati o, the K-->pi pi three-point function divided by either K and pi meson two-point functions or K meson two-point function and I = 2 pi pi fou r-point function; the two different methods yield consistent results. Finite size effects are examined with calculations made on 24(3) X 64 and 32(3) X 64 lattices, and are shown that they are explained by one- loop effects of chiral perturbation theory. The lattice amplitude is c onverted to the continuum value by employing a one-loop calculation of chiral perturbation theory, yielding a value in agreement with experi ment if extrapolated to the chiral limit. We also report on the K meso n B parameter B-K obtained from the K+ --> pi(+) pi(0) amplitude using chiral perturbation theory. [S0556-2821(98)03417-1]