Order αs4 QCD corrections to Z and τ decays
Order αs4 QCD corrections to Z and τ decays
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DOI：
10.1103/physrevlett.101.012002
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发表时间：
2008-07-04
影响因子：
8.6
通讯作者：
Kuehn, J. H.
中科院分区：
文献类型：
--
作者：
Baikov, P. A.;Chetyrkin, K. G.;Kuehn, J. H.
利用最近发展的评价微扰QCD中五环振幅的方法，对电子-正电子湮灭成强子的截面的非单重态部分以及Z玻色子和tau轻子成强子的衰变速率的alpha(4)(s)阶修正进行了评估。新的项导致了扰动序列的显著稳定，减少了从这些测量中提取的强耦合常数α (s)的理论不确定性，并导致了中心值的小位移，使两个中心值更靠近。在截然不同的能量下测量的两个α (s)值之间的一致性构成了对渐近自由的惊人检验。结合Z和tau衰变的结果，我们发现α (s)(M(Z))=0.1198 +/- 0.0015是α (4)(s)阶强耦合常数的最精确和目前唯一的结果之一。
Using recently developed methods for the evaluation of five-loop amplitudes in perturbative QCD, corrections of order alpha(4)(s) 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 tau 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 alpha(s), 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 alpha(s) measured at vastly different energies constitutes a striking test of asymptotic freedom. Combining the results from Z and tau decays we find alpha(s)(M(Z))=0.1198 +/- 0.0015 as one of the most precise and presently only result for the strong coupling constant in order alpha(4)(s).