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

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, ATLAS Collaboration

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Abstract

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
Original languageEnglish
Pages (from-to)228-246
Number of pages19
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume756
DOIs
Publication statusPublished - 2016

Bibliographical note

Cited By :16

Export Date: 8 March 2018

Subject classification (UKÄ)

  • Subatomic Physics

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