Yerevan Physics Institute, Yerevan, Armenia.
Institut für Hochenergiephysik der OeAW, Wien, Austria.
Phys Rev Lett. 2014 Jun 13;112(23):231802. doi: 10.1103/PhysRevLett.112.231802. Epub 2014 Jun 9.
The first observation of the associated production of a single top quark and a W boson is presented. The analysis is based on a data set corresponding to an integrated luminosity of 12.2 fb(-1) of proton-proton collisions at sqrt[s] = 8 TeV recorded by the CMS experiment at the LHC. Events with two leptons and a jet originating from a b quark are selected. A multivariate analysis based on kinematic and topological properties is used to separate the signal from the dominant tt background. An excess consistent with the signal hypothesis is observed, with a significance which corresponds to 6.1 standard deviations above a background-only hypothesis. The measured production cross section is 23.4 ± 5.4 pb, in agreement with the standard model prediction.
首次观察到单个顶夸克和 W 玻色子的关联产生。该分析基于 CMS 实验在 LHC 上记录的质子-质子对撞的 sqrt[s] = 8 TeV 时对应的 12.2 fb(-1)的积分亮度数据。选择了具有两个轻子和源自 b 夸克的喷注的事件。基于运动学和拓扑性质的多元分析用于将信号与主要的 tt 背景区分开来。观察到与信号假设一致的过剩，其显著性对应于仅背景假设的 6.1 个标准偏差以上。测量的产生横截面为 23.4 ± 5.4 pb，与标准模型预测相符。
