Violations of quark-hadron duality in low-energy determinations of ?s

A bstract Using the spectral functions measured in ? decays, we investigate actual numerical impact of duality violations on extraction strong coupling. These effects are tiny standard ? s ( $$ {m}_{\tau}^2 m ? 2 ) determinations from integrated distributions hadronic spectrum with pinched weights, or total width. The pinched-weight factors suppress very efficiently duality, making their negligible comparison larger perturbative uncertainties. However, combined fits and duality-violation parameters, performed non-protected subject to large systematic errors associated assumed modelling effects. uncertainties have not been taken into account published analyses, based specific models quark-hadron duality.