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

, ; Aaboud, M; Åkesson, Torsten LU ; Bocchetta, Simona LU ; Corrigan, Eric LU ; Doglioni, Caterina LU ; Brottmann Hansen, Eva LU ; Hedberg, Vincent LU ; Jarlskog, Göran LU and Kalderon, Charles LU , et al. (2018) In Journal of High Energy Physics 2018(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... (More)
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.]. © 2018, The Author(s). (Less)
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subject
keywords
Hadron-Hadron scattering (experiments)
in
Journal of High Energy Physics
volume
2018
issue
7
publisher
Springer
external identifiers
  • scopus:85051260203
ISSN
1126-6708
DOI
10.1007/JHEP07(2018)176
language
English
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yes
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b51968e6-4b04-4fa1-9a52-92faf4503431
date added to LUP
2018-09-12 07:39:26
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2018-10-03 09:50:21
@article{b51968e6-4b04-4fa1-9a52-92faf4503431,
  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.]. © 2018, The Author(s).},
  articleno    = {176},
  author       = {,  and Aaboud, M and Åkesson, Torsten and Bocchetta, Simona and Corrigan, Eric and Doglioni, Caterina and Brottmann Hansen, Eva and Hedberg, Vincent and Jarlskog, Göran and Kalderon, Charles and Kellermann, Edgar and Konya, Balazs and Lytken, Else and Mankinen, Katja and Mjörnmark, Ulf and Pöttgen, Ruth and Poulsen, Trine and Smirnova, Oxana and Viazlo, Oleksandr and Zwalinski, L},
  issn         = {1126-6708},
  keyword      = {Hadron-Hadron scattering (experiments)},
  language     = {eng},
  number       = {7},
  publisher    = {Springer},
  series       = {Journal of High Energy Physics},
  title        = {Search for flavour-changing neutral current top-quark decays t → qZ in proton-proton collisions at √s=13 TeV with the ATLAS detector},
  url          = {http://dx.doi.org/10.1007/JHEP07(2018)176},
  volume       = {2018},
  year         = {2018},
}