A precise $\alpha_s$ determination from the R-improved QCD Static Energy
J.M. Mena Valle
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Pre-published on: January 14, 2026
Published on:
Abstract
The strong coupling $\alpha_s$ is determined with high precision from fits to lattice QCD simulations on the static energy. Our theoretical setup relies on R-improving the three-loop fixed-order prediction for the static energy
by removing its $u=1/2$ renormalon and summing up the associated large (infrared) logarithms which, in combination with radius-dependent renormalization scales (called profile functions), extend the validity of perturbation theory to distances up to $\sim 0.5\,$fm.
Furthermore, we resum large ultrasoft logarithms to N$^3$LL accuracy using
renormalization group evolution. We find that the standard four-loop R-evolution treats N$^4$LL and higher-order remnants asymmetrically, hence, we also account for this potential bias.
Our estimate of the perturbative uncertainty is based on a random scan over the parameters specifying the profile functions and the treatment of R-evolution.
We explore the dependence of the extracted $\alpha_s$ value on the smallest and largest distances included in the dataset, on how R-evolution is treated,
on how the fit is performed, and on the accuracy of ultrasoft resummation. From our final analysis, after evolving to the $Z$-pole we obtain $\alpha^{(n_f=5)}_s(m_Z)=0.1166\pm 0.0009$, compatible with the world average with a comparable uncertainty.
DOI: https://doi.org/10.22323/1.485.0238
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