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We revisit the QCD sum-rule treatment of the isospin-breaking axialcorrelator in light of the recent claim that a previous treatment producedresults incompatible with known chiral constraints. The source of the error inthe previous analysis is identified, and a corrected version of the sum-ruletreatment obtained. It is then shown that, using input from chiral perturbationtheory, one may use the resulting sum rule to extract information on theleading chiral behavior of isospin-breaking parameters associated with thecoupling of excited pseudoscalar resonances to the axial currents. A ratheraccurate extraction is possible for the case of the eta'. Demanding stabilityof the sum-rule analysis also allows us to improve the upper bound on thefourth-order low-energy constant, L_7.Comment: 20 pages (RevTeX), 1 figure (epsf

QCD sum rules for the isospin-breaking axial correlator with correct chiral behavior