NNLO low-energy constants from flavor-breaking chiral sum rules based on hadronic τ -decay data

Using spectral data from nonstrange and strange hadronic τ decays, flavor-breaking chiral sum rules involving the flavor ud and us current-current two-point functions are constructed and used to determine the SU(3) next-to-next-to-leading order (NNLO) low-energy constant combinations C61r, C12r+C61r+C80r and C12r-C61r+C80r. The first of these determinations updates the results of an earlier analysis by Dürr and Kambor, while the latter two are new. The error on C12r+C61r+C80r is particularly small. Comparisons are made to model estimates for these quantities. The role of the third combination in significantly improving the determination of the next-to-leading order low-energy constant L10r from NNLO analyses of the flavor ud V-A correlator is also highlighted. © 2014 American Physical Society.