αb>sb> and |Vb>csb>| determination, and CKM unitarity test, from W decays at NNLO

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• 作者：David d'Enterria^a ; ^dde@cern.ch ; Matej Srebre^a ; ^b
• 刊名：Physics Letters B
• 出版年：2016
• 出版时间：10 December 2016
• 年：2016
• 卷：763
• 期：Complete
• 页码：465-471
• 全文大小：621 K
• 卷排序：763

文摘

The hadronic (ΓhadW) and total (ΓtotW) widths of the W boson, computed at least at next-to-next-to-leading-order (NNLO) accuracy, are combined to derive a new precise prediction for the hadronic W branching ratio BhadW ≡ ΓhadW/ΓtotW=0.682±0.011par, using the experimental Cabibbo–Kobayashi–Maskawa (CKM) matrix elements, with uncertainties dominated by the input parameters of the calculations, or BhadW=0.6742±0.0002th±0.0001par assuming CKM unitarity. Comparing the theoretical predictions and experimental measurements for various W decay observables, the NNLO strong coupling constant at the Z pole, αs(mZ2)=0.117±0.042exp±0.004th±0.001par, as well as the charm-strange CKM element, |Vcs|=0.973±0.004exp±0.002par|Vcs|=0.973±0.004exp±0.002par, can be extracted under different assumptions. We also show that W decays provide today the most precise test of CKM unitarity for the 5 quarks lighter than mWmW, ∑u,c,d,s,b|Vij|2=1.999±0.008exp±0.001th∑u,c,d,s,b|Vij|2=1.999±0.008exp±0.001th. Perspectives for αsαs and |Vcs||Vcs| extractions from W decays measurements at the LHC and future e+e−e+e− colliders are presented.