Abstract
Using recently developed methods for the evaluation of five-loop amplitudes in perturbative QCD, corrections of order for the nonsinglet part of the cross section for electron-positron annihilation into hadrons and for the decay rates of the boson and the lepton into hadrons are evaluated. The new terms lead to a significant stabilization of the perturbative series, to a reduction of the theory uncertainly in the strong coupling constant , as extracted from these measurements, and to a small shift of the central value, moving the two central values closer together. The agreement between two values of measured at vastly different energies constitutes a striking test of asymptotic freedom. Combining the results from and decays we find as one of the most precise and presently only result for the strong coupling constant in order .
- Received 11 January 2008
DOI:https://doi.org/10.1103/PhysRevLett.101.012002
©2008 American Physical Society