Additional isospin-breaking effects in epsilon '/epsilon

In the analysis of epsilon'/epsilon it has been traditional to consider the isospin-breaking effects arising from electroweak-penguin contributions an d from pi(0)-eta,eta' mixing, yet additional isospin-violating effects exis t. In particular, we study the isospin violation which arises from the u-d quark mass difference in the hadronization of the gluonic penguin operator, engendering contributions of an effective Delta I = 3/2 character. Using c hiral perturbation theory and the factorization approximation for the hadro nic matrix elements, we find within a specific model for the low-energy con stants that we can readily accommodate an increase in epsilon'/epsilon by a factor of two. (C) 1999 Published by Elsevier Science B.V. All lights rese rved.