Observation of the associated production of a single top quark and a W boson in pp collisions at sqrt[s] = 8 TeV.

Abstract

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 12.2fb-1 of proton-proton collisions at s=8TeV 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 tt̄ 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±5.4pb, in agreement with the standard model prediction. © 2014 CERN, for the CMS Collaboration.National Natural Science Foundation of ChinaMassachusetts Department of Fish and GameScience and Technology Facilities CouncilRussian Foundation for Basic ResearchCanadian Anesthesiologists' SocietyNeurosurgical Research FoundationNational Science Council TaiwanNational Institutes of HealthResearch Promotion Foundation