Chiral low-energy constants L10 and C87 from hadronic τ decays

Using recent precise hadronic τ-decay data on the V – A spectral function and general properties of QCD such as analyticity, the operator product expansion (OPE) and chiral perturbation theory (χPT), we get accurate values for the QCD chiral order parameters and . At order p4 we obtain , whereas at order p6 we get and .