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arXiv 0801.1821hep-ph
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α_s^4级强子Z衰变和τ衰变

Hadronic Z- and tau-Decays in Order alpha_s^4

P. A. Baikov, K. G. Chetyrkin, J. H. Kühn

摘要:

利用最近发展起来的计算微扰QCD中五圈振幅的方法,计算了电子正电子湮没成强子的截面以及Z玻色子和τ轻子衰变成强子的速率的α_s^4级修正。新的条款导致一个显着的稳定性的微扰系列,减少理论的不确定性,在强耦合常数α_s,从这些测量中提取,和一个小的移动的中心值,移动两个中心值更接近。在能量相差很大的情况下测得的两个α s值之间的一致性构成了对渐近自由的一个惊人的检验。结合Z衰变和τ衰变的结果,我们发现α_s(M_Z)=0.1198 \pm 0.0015,这是目前最精确的结果之一,也是目前唯一的α_s ^[4]级强耦合常数的结果。

英文摘要:

Using recently developed methods for the evaluation of five-loop amplitudes in perturbative QCD, corrections of order alpha_s^4 for the cross section of 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 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 \pm 0.0015 as one of the most precise and presently only result for the strong coupling constant in order alpha_s^4.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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