Division of High Energy Physics, Department of Physics, University of Helsinki and Helsinki Institute of Physics, FIN-00014, Helsinki, Finland.
Istituto Nazionale di Fisica Nucleare, Sezione di Padova-Trento, I-35131 Padova, Italy.
Phys Rev Lett. 2013 Feb 15;110(7):071801. doi: 10.1103/PhysRevLett.110.071801. Epub 2013 Feb 13.
The first observation of the production of a W boson with a single charm quark (c) jet in pp[over ¯] collisions at √s=1.96 TeV is reported. The analysis uses data corresponding to 4.3 fb(-1), recorded with the CDF II detector at the Fermilab Tevatron. Charm quark candidates are selected through the identification of an electron or muon from charm-hadron semileptonic decay within a hadronic jet, and a Wc signal is observed with a significance of 5.7 standard deviations. The production cross section σ(Wc)(p(Tc)>20 GeV/c,|η(c)|<1.5)×B(W→ℓν) is measured to be 13.6(-3.1)(+3.4) pb and is in agreement with theoretical expectations. From this result the magnitude of the quark-mixing matrix element V(cs) is derived, |V(cs)|=1.08±0.16 along with a lower limit of |V(cs)|>0.71 at the 95% confidence level, assuming that the Wc production through c to s quark coupling is dominant.
首次观察到在 pp[over ¯] 碰撞中单个魅夸克 (c) 喷注中产生 W 玻色子。该分析使用了在费米实验室 Tevatron 的 CDF II 探测器记录的对应于 4.3 fb(-1) 的数据。通过在强子喷注内识别来自魅子半轻子衰变的电子或缪子来选择魅夸克候选者，并观察到 Wc 信号，其显著性为 5.7 个标准偏差。测量到 Wc(p(Tc)>20 GeV/c,|η(c)|<1.5)×B(W→ℓν)的产生截面 σ(Wc)为 13.6(-3.1)(+3.4) pb，与理论预期相符。根据这一结果，推导出了夸克混合矩阵元 V(cs)的大小，|V(cs)|=1.08±0.16，同时在 95%置信水平下，假设 Wc 通过 c 到 s 夸克耦合的产生占主导地位，|V(cs)|>0.71 的下限。
