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Search for flavour-changing neutral currents in processes with one top quark and a photon using 81 fb−1 of pp collisions at √s = 13 TeV with the ATLAS experiment

Aad, G; Abbott, B; Abbott, DC; Abed Abud, A; Abeling, K; Abhayasinghe, DK; Abidi, SH; ... Araujo Ferraz, V; + view all (2020) Search for flavour-changing neutral currents in processes with one top quark and a photon using 81 fb−1 of pp collisions at √s = 13 TeV with the ATLAS experiment. Physics Letters B , 800 , Article 135082. 10.1016/j.physletb.2019.135082. Green open access

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Abstract

A search for flavour-changing neutral current (FCNC) events via the coupling of a top quark, a photon, and an up or charm quark is presented using 81 fb−1 of proton–proton collision data taken at a centre-ofmass energy of 13 TeV with the ATLAS detector at the LHC. Events with a photon, an electron or muon, a b-tagged jet, and missing transverse momentum are selected. A neural network based on kinematic variables differentiates between events from signal and background processes. The data are consistent with the background-only hypothesis, and limits are set on the strength of the tqγ coupling in an effective field theory. These are also interpreted as 95% CL upper limits on the cross section for FCNC tγ production via a left-handed (right-handed) tuγ coupling of 36 fb (78 fb) and on the branching ratio for t → γ u of 2.8 × 10−5 (6.1 × 10−5). In addition, they are interpreted as 95% CL upper limits on the cross section for FCNC tγ production via a left-handed (right-handed) tcγ coupling of 40 fb (33 fb) and on the branching ratio for t → γ c of 22 × 10−5 (18 × 10−5)

Type: Article
Title: Search for flavour-changing neutral currents in processes with one top quark and a photon using 81 fb−1 of pp collisions at √s = 13 TeV with the ATLAS experiment
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.physletb.2019.135082
Publisher version: https://doi.org/10.1016/j.physletb.2019.135082
Language: English
Additional information: Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI: https://discovery.ucl.ac.uk/id/eprint/10087286
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