In the analysis of ∈′/∈ it has been traditional to consider the isospin-breaking effects arising from electroweak-penguin contributions and from π0-η,η′ mixing, yet additional isospin-violating effects exist. 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 ΔI = 3/2 character. Using chiral perturbation theory and the factorization approximation for the hadronic matrix elements, we find within a specific model for the low-energy constants that we can readily accommodate an increase in ∈′/∈ by a factor of two.
|Number of pages||8|
|Journal||Physics Letters B|
|Publication status||Published - 1999|