Application of Padé approximants to determination of αs(MZ2) from hadronic event shape observables in e+e− annihilation

We have applied Padé approximants to perturbative QCD calculations of event shape observables in e+e− → hadrons. We used the exact O(αs2) prediction and the [01] Padé approximant to estimate the O(αs3) term for 15 observables, and in each case determined αs(MZ2) from comparison with hadronic Z0 decay data from the SLD experiment. We found the scatter among the αs(MZ2) values to be significantly reduced compared with the standard O(αs2) determination, implying that the Padé method provides at least a partial approximation of higher-order perturbative contributions to event shape observables.