High precision determination of αs from a global fit of jet rates

A bstract We present state-of-the-art extractions of the strong coupling based on N 3 LO+NNLL accurate predictions for the two-jet rate in the Durham clustering algorithm at e + e − collisions, as well as a simultaneous fit of the two- and three-jet rates taking into account correlations between the two observables. The fits are performed on a large range of data sets collected at the LEP and PETRA colliders, with energies spanning from 35 GeV to 207 GeV. Owing to the high accuracy of the predictions used, the perturbative uncertainty is considerably smaller than that due to hadronization. Our best determination at the Z mass is α s ( M Z ) = 0 . 11881 ± 0 . 00063(exp . ) ± 0 . 00101(hadr . ) ± 0 . 00045(ren . ) ± 0 . 00034(res . ), which is in agreement with the latest world average and has a comparable total uncertainty.