Phenomenological Analysis of a Dimension-Two Operator in QCD and its Impact on $\alpha_{s}(M_{ au})$

摘要

Fits to the ARGUS data on hadronic decays of the tau-lepton, which determinethe vector and axial-vector spectral functions, are used in order to determinethe size of a dimension $d=2$ term in the Operator Product Expansion.Constraints from the first Weinberg sum rule (in the chiral limit) are enforcedin order to reduce the uncertainty of this determination. Results for the $d=2$operator are consistent with a quadratic dependence on $\Lambda_{QCD}$. Theimpact of this term on the extraction of $\alpha_{s}(M_{\tau})$ is assessed.