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https://hdl.handle.net/10316/107742
Title: | Search for flavour-changing neutral current top-quark decays t → qZ in proton-proton collisions at √s=13 TeV with the ATLAS detector | Authors: | Santos, S. P. Amor dos Fiolhais, M. C. N. Galhardo, B. Veloso, F. Wolters, H. ATLAS Collaboration |
Keywords: | Hadron-Hadron scattering (experiments) | Issue Date: | 2018 | Publisher: | Springer Nature | Serial title, monograph or event: | Journal of High Energy Physics | Volume: | 2018 | Issue: | 7 | 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. | URI: | https://hdl.handle.net/10316/107742 | DOI: | 10.1007/JHEP07(2018)176 | Rights: | openAccess |
Appears in Collections: | FCTUC Física - Artigos em Revistas Internacionais |
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Search-for-flavourchanging-neutral-current-topquark-decays-t--qZ-in-protonproton-collisions-at-s13-TeV-with-the-ATLAS-detectorJournal-of-High-Energy-Physics.pdf | 1.38 MB | Adobe PDF | View/Open |
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