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arXiv · 1805.08176

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

Diogo Boito·Maarten Golterman·Alexander Keshavarzi·Kim Maltman·Daisuke Nomura·Santiago Peris·Thomas Teubner
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Abstract

We use a new compilation of the hadronic $R$-ratio from available data for the process $e^+e^-\to\mbox{hadrons}$ to determine the strong coupling, $α_s$. We make use of all data for the $R$-ratio from threshold to a center-of-mass energy of 2 GeV by employing finite-energy sum rules. Data above 2 GeV, for which at present far fewer high-precision experimental data are available, do not provide much additional constraint but are fully consistent with the values for $α_s$ we obtain. Quoting our results at the $τ$ mass to facilitate comparison to the results obtained from analogous analyses of hadronic $τ$-decay data, we find $α_s(m_τ^2)=0.298\pm 0.016\pm 0.006$ in fixed-order perturbation theory, and $α_s(m_τ^2)=0.304\pm 0.018\pm 0.006$ in contour-improved perturbation theory, where the first error is statistical, and the second error reflects our estimate of various systematic effects. These values are in good agreement with a recent determination from the OPAL and ALEPH data for hadronic $τ$ decays.

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Diogo Boito, Maarten Golterman, Alexander Keshavarzi, Kim Maltman, Daisuke Nomura, Santiago Peris, Thomas Teubner. 2018-05-21. The strong coupling from $e^+e^-\to$ hadrons below charm. https://doi.org/10.1103/physrevd.98.074030

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