Division of High Energy Physics, Department of Physics, University of Helsinki, FIN-00014, Helsinki, Finland; Helsinki Institute of Physics, FIN-00014, Helsinki, Finland.
Istituto Nazionale di Fisica Nucleare, Sezione di Padova, Italy and University of Padova, I-35131 Padova, Italy.
Phys Rev Lett. 2014 Jun 13;112(23):231805. doi: 10.1103/PhysRevLett.112.231805. Epub 2014 Jun 9.
The first search for single-top-quark production from the exchange of an s-channel virtual W boson using events with an imbalance in the total transverse energy, b-tagged jets, and no identified leptons is presented. Assuming the electroweak production of top quarks of mass 172.5 GeV/c(2) in the s channel, a cross section of 1.12(-0.57)(+0.61) (stat+syst) pb with a significance of 1.9 standard deviations is measured. This measurement is combined with the result obtained from events with an imbalance in total transverse momentum, b-tagged jets, and exactly one identified lepton, yielding a cross section of 1.36(-0.32)(+0.37) (stat+syst) pb, with a significance of 4.2 standard deviations.
首次利用总横动量不平衡、带 b 标签的喷注且没有识别出的轻子的事件，搜索 s 通道中虚 W 玻色子交换产生的单个顶夸克事例。在假设 172.5GeV/c(2) 质量的顶夸克通过电弱过程在 s 通道产生的情况下，测量到截面为 1.12(-0.57)(+0.61) pb（统计+系统），置信度为 1.9 个标准差。该测量结果与总横动量不平衡、带 b 标签的喷注且仅有一个识别出的轻子的事例的结果进行了组合，得到截面为 1.36(-0.32)(+0.37) pb（统计+系统），置信度为 4.2 个标准差。
