The strong coupling from $e^+e^-\to$~hadrons

Diogo Boito, Maarten Golterman, Alex Keshavarzi, Kim Maltman, Daiskuke Nomura, Santiago Peris, Thomas Teubner

SciPost Phys. Proc. 1, 035 (2019) · published 21 February 2019

Proceedings event

The 15th International Workshop on Tau Lepton Physics


We use a new compilation of the hadronic $R$-ratio from available data for the process $e^+e^-\to$ hadrons below the charm mass to determine the strong coupling $\alpha_s$, using finite-energy sum rules. Quoting our results at the $\tau$ mass to facilitate comparison to the results obtained from similar analyses of hadronic $\tau$-decay data, we find $\alpha_s(m_\tau^2)=0.298\pm 0.016\pm 0.006$ in fixed-order perturbation theory, and $\alpha_s(m_\tau^2)=0.304\pm 0.018\pm 0.006$ in contour-improved perturbation theory, where the first error is statistical, and the second error combines various systematic effects. These values are in good agreement with a recent determination from the OPAL and ALEPH data for hadronic $\tau$ decays. We briefly compare the $R(s)$-based analysis with the $\tau$-based analysis.

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