Improved determination of the electroweak penguin contribution to epsilon '/epsilon in the chiral limit

摘要

We perform a finite energy sum rule analysis of the flavor ud two-point V-A current correlator, DeltaPi(Q(2)). The analysis, which is performed using both the ALEPH and OPAL databases for the V-A spectral function, Deltarho, 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 is an element of'/is an element of = (-15.0 +/- 2.7) x 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. (C) 2003 Elsevier Science B.V. All rights reserved. [References: 52]