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arXiv · hep-ph/9909202

Additional Isospin-Breaking Effects in ε^\prime/ε

S. Gardner·G. Valencia
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Abstract

In the analysis of ε^\prime/εit has been traditional to consider the isospin-breaking effects arising from electroweak-penguin contributions and from π^0-ηand π^0-η^\prime 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 ε^\prime/εby a factor of two.

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S. Gardner, G. Valencia. 1999-09-13. Additional Isospin-Breaking Effects in ε^\prime/ε. https://doi.org/10.1016/s0370-2693(99)01164-8

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