The strong coupling from tau decays without prejudice

Understand

We review our recent determination of the strong coupling \alpha_s from the OPAL data for non-strange hadronic tau decays.

• We find that \alpha_s(m^2_\tau) =0.325+-0.018 using fixed-order perturbation theory, and \alpha_s(m^2_\tau)=0.347+-0.025 using contour-improved perturbation theory.
• At present, these values supersede any earlier determinations of the strong coupling from hadronic tau decays, including those from ALEPH data.