## Abstract

In the analysis of ∈′/∈ it has been traditional to consider the isospin-breaking effects arising from electroweak-penguin contributions and from π^{0}-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 language | English |
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Pages (from-to) | 355-362 |

Number of pages | 8 |

Journal | Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics |

Volume | 466 |

Issue number | 2-4 |

DOIs | |

State | Published - 1999 |

### Bibliographical note

Funding Information:The work of S.G. and G.V. is supported in part by the DOE under contract numbers DE-FG02-96ER40989 and DE-FG02-92ER40730, respectively. We thank J.F. Donoghue, C.-J. David Lin, and M.B. Wise for useful conversations, and we thank J. Bijnens for pointing out Ref. [19] . We are grateful to the Institute for Nuclear Theory at the University of Washington, the SLAC Theory Group, the Summer Visitor's Program of the Fermilab Theory Group, and M.B. Wise for hospitality during the completion of this work.

### Funding

The work of S.G. and G.V. is supported in part by the DOE under contract numbers DE-FG02-96ER40989 and DE-FG02-92ER40730, respectively. We thank J.F. Donoghue, C.-J. David Lin, and M.B. Wise for useful conversations, and we thank J. Bijnens for pointing out Ref. [19] . We are grateful to the Institute for Nuclear Theory at the University of Washington, the SLAC Theory Group, the Summer Visitor's Program of the Fermilab Theory Group, and M.B. Wise for hospitality during the completion of this work.

Funders | Funder number |
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U.S. Department of Energy EPSCoR | DE-FG02-92ER40730, DE-FG02-96ER40989 |

## ASJC Scopus subject areas

- Nuclear and High Energy Physics