Search for single top-quark production via flavour-changing neutral currents at 8 TeV with the ATLAS detector

Barton, Adam Edward and Beattie, Michael and Borissov, Guennadi and Bouhova-Thacker, Evelina Vassileva and Dearnaley, William and Fox, Harald and Grimm, Kathryn Ann Tschann and Henderson, Robert Charles William and Hughes, Gareth and Jones, Roger William Lewis and Kartvelishvili, Vakhtang and Long, Robin Eamonn and Love, Peter Allan and Maddocks, Harvey and Skinner, Malcolm and Smizanska, Maria and Walder, James William and Wharton, Andy (2016) Search for single top-quark production via flavour-changing neutral currents at 8 TeV with the ATLAS detector. European Physical Journal C: Particles and Fields, 76 (2). ISSN 1434-6044

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Abstract

A search for single top-quark production via flavour-changing neutral current processes from gluon plus up- or charm-quark initial states in proton–proton collisions at the LHC is presented. Data collected with the ATLAS detector in 2012 at a centre-of-mass energy of 8 TeV and corresponding to an integrated luminosity of 20.3 fb−1−1 are used. Candidate events for a top quark decaying into a lepton, a neutrino and a jet are selected and classified into signal- and background-like candidates using a neural network. No signal is observed and an upper limit on the production cross-section multiplied by the t→Wbt→Wb branching fraction is set. The observed 95 % CL limit is σqg→t×B(t→Wb)<3.4pbσqg→t×B(t→Wb)<3.4pb and the expected 95 % CL limit is σqg→t×B(t→Wb)<2.9pbσqg→t×B(t→Wb)<2.9pb. The observed limit can be interpreted as upper limits on the coupling constants of the flavour-changing neutral current interactions divided by the scale of new physics κugt/Λ<5.8×10−3TeV−1κugt/Λ<5.8×10−3TeV−1 and κcgt/Λ<13×10−3TeVκcgt/Λ<13×10−3TeV and on the branching fractions B(t→ug)<4.0×10−5B(t→ug)<4.0×10−5and B(t→cg)<20×10−5B(t→cg)<20×10−5.

Item Type: Journal Article
Journal or Publication Title: European Physical Journal C: Particles and Fields
Uncontrolled Keywords: /dk/atira/pure/subjectarea/asjc/2200/2201
Subjects:
Departments: Faculty of Science and Technology > Physics
ID Code: 79631
Deposited By: ep_importer_pure
Deposited On: 18 May 2016 10:10
Refereed?: Yes
Published?: Published
Last Modified: 18 Nov 2019 02:48
URI: https://eprints.lancs.ac.uk/id/eprint/79631

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