Strange quark mass from sum rules with improved perturbative QCD convergence

The strange quark mass is determined from a QCD Finite Energy Sum Rule (FESR) optimized to reduce considerably the systematic uncertainties arising from the hadronic resonance sector, as well as from the poor convergence of the pseudoscalar correlator in perturbative QCD. The former is achieved by introducing a suitable integration kernel in the Cauchy integral in the complex squared energy plane. The latter is obtained by optimizing the perturbative expansion to accelerate its convergence. The result for the strange quark mass in the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$ \overline{MS} $\end{document} scheme at a scale of 2 GeV is \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$ {{\overline{m}}_s}\left( {2\mathrm{GeV}} \right)=94\pm 9 $\end{document} MeV.