ChPT parameters from τ-decay data

Using the updated ALEPH V−A spectral function from τ decays, we determine the lowest spectral moments of the left-right correlator and extract dynamical information on order parameters of the QCD chiral symmetry breaking. Uncertainties associated with violations of quark-hadron duality are estimated from the data, imposing all known short-distance constraints on a resonance-based parametrization. Employing proper pinched weight functions, we obtain an accurate determination of the effective chiral couplings L10eff and C8eff7 and the dimension-six and -eight contributions in the Operator Product Expansion.