Additional isospin-breaking effects in ∈′/∈

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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.

Original languageEnglish
Pages (from-to)355-362
Number of pages8
JournalPhysics Letters B
Issue number2-4
Publication statusPublished - 1999
Externally publishedYes

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