Evidence for single top-quark production in the s-channel in proton–proton collisions at √s=8 TeV with the ATLAS detector using the Matrix Element Method

Summary, in English

This Letter presents evidence for single top-quark production in the s-channel using proton–proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS detector at the CERN Large Hadron Collider. The analysis is performed on events containing one isolated electron or muon, large missing transverse momentum and exactly two b-tagged jets in the final state. The analysed data set corresponds to an integrated luminosity of 20.3 fb−1. The signal is extracted using a maximum-likelihood fit of a discriminant which is based on the matrix element method and optimized in order to separate single-top-quark s-channel events from the main background contributions, which are top-quark pair production and W boson production in association with heavy-flavour jets. The measurement leads to an observed signal significance of 3.2 standard deviations and a measured cross-section of σs=4.8±0.8(stat.)−1.3 +1.6(syst.) pb, which is consistent with the Standard Model expectation. The expected significance for the analysis is 3.9 standard deviations. © 2016 CERN for the benefit of the ATLAS Collaboration

• Author: G Aad; B. Abbott; J Abdallah; O Abdinov; R Aben; M Abolins; Torsten Åkesson; Simona Bocchetta; Lene Bryngemark; Caterina Doglioni; Anders Floderus; Anthony Hawkins; Vincent Hedberg; Jenny Ivarsson; Göran Jarlskog; Else Lytken; Ulf Mjörnmark; Oxana Smirnova; Oleksandr Viazlo
• Department/s: Particle and nuclear physics; eSSENCE: The e-Science Collaboration
• Publishing year: 2016
• Language: English
• Pages: 228-246
• Publication/Series: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
• Volume: 756
• Links: http://dx.doi.org/10.1016/j.physletb.2016.03.017
• Document type: Journal article
• Publisher: Elsevier
• Topic: Subatomic Physics
• Status: Published
• ISBN/ISSN/Other: ISSN: 0370-2693