Search for flavour-changing neutral current top-quark decays tqZ in proton-proton collisions at √s=13 TeV with the ATLAS detector



Aaboud, M, Aad, G, Abbott, B, Abdinov, O, Abeloos, B, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H
et al (show 2859 more authors) (2018) Search for flavour-changing neutral current top-quark decays tqZ in proton-proton collisions at √s=13 TeV with the ATLAS detector JOURNAL OF HIGH ENERGY PHYSICS, 2018 (7). 176-. ISSN 1029-8479, 1029-8479

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Abstract

A search for flavour-changing neutral-current processes in top-quark decays is presented. Data collected with the ATLAS detector from proton-proton collisions at the Large Hadron Collider at a centre-of-mass energy of s=13 TeV, corresponding to an integrated luminosity of 36.1 fb−1, are analysed. The search is performed using top-quark pair events, with one top quark decaying through the t → qZ (q = u, c) flavour-changing neutral-current channel, and the other through the dominant Standard Model mode t → bW. Only Z boson decays into charged leptons and leptonic W boson decays are considered as signal. Consequently, the final-state topology is characterized by the presence of three isolated charged leptons (electrons or muons), at least two jets, one of the jets originating from a b-quark, and missing transverse momentum from the undetected neutrino. The data are consistent with Standard Model background contributions, and at 95% confidence level the search sets observed (expected) upper limits of 1.7 × 10−4 (2.4 × 10−4) on the t → uZ branching ratio and 2.4 × 10−4 (3.2 × 10−4) on the t → cZ branching ratio, constituting the most stringent limits to date.[Figure not available: see fulltext.].

Item Type: Article
Additional Information: 42 pages in total, author list starting page 26, 4 figures, 11 tables, published in JHEP. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/TOPQ-2017-06
Uncontrolled Keywords: Hadron-Hadron scattering (experiments)
Depositing User: Symplectic Admin
Date Deposited: 10 Sep 2018 06:45
Last Modified: 22 May 2026 21:08
DOI: 10.1007/JHEP07(2018)176
Open Access URL: https://link.springer.com/article/10.1007/JHEP07(2...
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3025940
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