Lattice calculation of matrix elements relevant for Delta I=1/2 rule and epsilon-prime

Abstract

We have gained enough statistical precision to distinguish signal from noise in matrix elements of all operators relevant for the Delta I=1/2 rule in kaon decays and for the direct CP violation parameter epsilon-prime. We confirm significant enhancement of Delta I=1/2 transitions observed in experiments, although a few large systematic uncertainties remain in our predictions: higher-order chiral corrections and lattice spacing dependence. The estimate of epsilon-prime parameter is further complicated by the problem of matching lattice and continuum operators.