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Improved Determination of the Electroweak Penguin Contribution to epsilon'/epsilon in the Chiral Limit

Vincenzo Cirigliano·John F. Donoghue·Eugene Golowich·Kim Maltman
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Abstract

We perform a finite energy sum rule analysis of the flavor ud two-point V-A current correlator, Delta Pi (Q^2). The analysis, which is performed using both the ALEPH and OPAL databases for the V-A spectral function, Delta rho, allows us to extract the dimension six V-A OPE coefficient, a_6, which is related to the matrix element of the electroweak penguin operator, Q_8, by chiral symmetry. The result for a_6 leads directly to the improved (chiral limit) determination epsilon'/epsilon = (- 15.0 +- 2.7) 10^{-4}. Determination of higher dimension OPE contributions also allows us to perform an independent test using a low-scale constrained dispersive analysis, which provides a highly nontrivial consistency check of the results.

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Vincenzo Cirigliano, John F. Donoghue, Eugene Golowich, Kim Maltman. 2002-11-27. Improved Determination of the Electroweak Penguin Contribution to epsilon'/epsilon in the Chiral Limit. https://doi.org/10.1016/s0370-2693(03)00010-8

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