EPSILON' EPSILON AT O(P(4)) IN THE CHIRAL EXPANSION/

After updating the determination of the combination of Kobayashi-Maska wa elements Im VtdVts according to our new estimate of the parameter (B) over cap(K)$, We study the CP-violating ratio epsilon'/epsilon by means of hadronic matrix elements computed to O(p(4)) in the chiral ex pansion. It is the first time that this order in chiral perturbation t heory is included. We also discuss the relevance of some O(p(2)) terms that are generally neglected in the calculation of the electroweak pe nguin matrix elements. The most important effect of this improved anal ysis is the substantial reduction (20%) of the leading electroweak pen guin matrix element and accordingly a reduced cancelation between the electroweak and gluon penguin contributions. The ratio epsilon'/epsilo n is thus larger than previously estimated and its predicted value enj oys a smaller uncertainty. We find epsilon'/epsilon = 1.7(-1.0)(+1.4) x 10(-3). Values positive and of the order of 10(-3) are therefore pre ferred. (C) 1998 Elsevier Science B.V.