Order alpha**4(s) QCD Corrections to Z and tau Decaysстатья
Статья опубликована в высокорейтинговом журнале
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Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:Using recently developed methods for the evaluation of five-loop amplitudes in perturbative QCD, corrections of order αs4 for the nonsinglet part of the cross section for electron-positron annihilation into hadrons and for the decay rates of the Z boson and the τ 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 αs, 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 αs measured at vastly different energies constitutes a striking test of asymptotic freedom. Combining the results from Z and τ decays we find αs(MZ)=0.1198±0.0015 as one of the most precise and presently only result for the strong coupling constant in order αs4.