Pade-Improved Extraction of ${\alpha }_s(M_{\tau })$ from $R_{\tau }$

Abstract

The perturbative series used to extract ${\alpha }_s(M_{\tau })$ from the $\tau$ hadronic width exhibits slow convergence. Asymptotic Pade-approximant and Pade summation techniques provide an estimate of these unknown higher-order effects, leading to values for ${\alpha }_s(M_{\tau })$ that are about 10% smaller than current estimates. Such a reduction improves the agreement of ${\alpha }_s(M_{\tau })$ with the QCD evolution of the strong coupling constant from ${\alpha }_s(M_z)$.

Comments: latex2e, 9 pages, 2 figures