Determination of $α_s(M_τ^2)$: a conformal mapping approach

Abstract

We discuss a new class of expansions in perturbative QCD, based on the technique of conformal mappings of the Borel plane, and apply them for the determination of $α_s$ from the hadronic decays of the $τ$ lepton. Using the expansion up to fifth order in the $\bar{\rm MS}$ scheme, the method leads to the prediction $α_s(M_τ^2)= 0.320\pm 0.011$.

6 pages, 2 figures. Talk given at the 11th International Workshop on Tau Lepton Physics, Manchester, UK, 13-17 September 2010