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

The ATLAS collaboration

doi:10.1007/JHEP07(2018)176

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

The ATLAS collaboration

National University of Science and Technology POLITEHNICA Bucharest
Dep Física and CEFITEC of Faculdade de Ciências e Tecnologia
NOVA University Lisbon
National Center for Energy, Nuclear Science and Technology
CERN
Mohamed I University
Aix-Marseille Université
University of Oklahoma
Azerbaijan National Academy of Sciences
IN2P3/CNRS
University of Toronto
University of California at Santa Cruz
University of Sussex
Tel Aviv University
Technion-Israel Institute of Technology
Stockholm University
Oskar Klein Centre
National Institute for Nuclear Physics
Abdus Salam International Centre for Theoretical Physics
King's College London
The University of Tokyo
AGH University of Krakow
Northern Illinois University
Ludwig Maximilian University of Munich
Rutherford Appleton Laboratory
Horia Hulubei National Institute of Physics and Nuclear Engineering
Laboratório de Instrumentação e Física Experimental de Partículas
University of Granada
Joint Institute for Nuclear Research
University of Rome Tor Vergata
Kyoto University
Lund University
University of Geneva
P.N. Lebedev Physical Institute of the Russian Academy of Sciences
University of Bologna
University of Victoria BC
Universidad Nacional de La Plata
Radboud University Nijmegen
Alexandru Ioan Cuza University of Iaşi
National Technical University of Athens
Czech Technical University in Prague
University of Salento
University of Milan
The University of Chicago

Research output: Contribution to journal › Article › peer-review

54 Scopus citations

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.].

Original language	English
Article number	176
Journal	Journal of High Energy Physics
Volume	2018
Issue number	7
DOIs	https://doi.org/10.1007/JHEP07(2018)176
State	Published - Jul 1 2018

Keywords

Hadron-Hadron scattering (experiments)

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10.1007/JHEP07(2018)176

Cite this

@article{ee4898ec936545359f969f63879d8aa4,

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

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.].",

keywords = "Hadron-Hadron scattering (experiments)",

author = "\{The ATLAS collaboration\} and M. Aaboud and G. Aad and B. Abbott and O. Abdinov and B. Abeloos and Abidi, \{S. H.\} and AbouZeid, \{O. S.\} and Abraham, \{N. L.\} and H. Abramowicz and H. Abreu and Y. Abulaiti and Acharya, \{B. S.\} and S. Adachi and L. Adamczyk and J. Adelman and M. Adersberger and T. Adye and Affolder, \{A. A.\} and Y. Afik and C. Agheorghiesei and Aguilar-Saavedra, \{J. A.\} and F. Ahmadov and G. Aielli and S. Akatsuka and H. Akerstedt and {\AA}kesson, \{T. P.A.\} and E. Akilli and Akimov, \{A. V.\} and Alberghi, \{G. L.\} and J. Albert and P. Albicocco and \{Alconada Verzini\}, \{M. J.\} and S. Alderweireldt and M. Aleksa and Aleksandrov, \{I. N.\} and C. Alexa and G. Alexander and T. Alexopoulos and M. Alhroob and B. Ali and M. Aliev and G. Alimonti and J. Alison and H. Arnold and \{Da Via\}, C. and V. Dao and J. Hobbs and J. Jia and G. Piacquadio and D. Tsybychev",

note = "Publisher Copyright: {\textcopyright} 2018, The Author(s).",

year = "2018",

month = jul,

day = "1",

doi = "10.1007/JHEP07(2018)176",

language = "English",

volume = "2018",

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T1 - Search for flavour-changing neutral current top-quark decays t → qZ in proton-proton collisions at √s=13 TeV with the ATLAS detector

AU - The ATLAS collaboration

AU - Aaboud, M.

AU - Aad, G.

AU - Abbott, B.

AU - Abdinov, O.

AU - Abeloos, B.

AU - Abidi, S. H.

AU - AbouZeid, O. S.

AU - Abraham, N. L.

AU - Abramowicz, H.

AU - Abreu, H.

AU - Abulaiti, Y.

AU - Acharya, B. S.

AU - Adachi, S.

AU - Adamczyk, L.

AU - Adelman, J.

AU - Adersberger, M.

AU - Adye, T.

AU - Affolder, A. A.

AU - Afik, Y.

AU - Agheorghiesei, C.

AU - Aguilar-Saavedra, J. A.

AU - Ahmadov, F.

AU - Aielli, G.

AU - Akatsuka, S.

AU - Akerstedt, H.

AU - Åkesson, T. P.A.

AU - Akilli, E.

AU - Akimov, A. V.

AU - Alberghi, G. L.

AU - Albert, J.

AU - Albicocco, P.

AU - Alconada Verzini, M. J.

AU - Alderweireldt, S.

AU - Aleksa, M.

AU - Aleksandrov, I. N.

AU - Alexa, C.

AU - Alexander, G.

AU - Alexopoulos, T.

AU - Alhroob, M.

AU - Ali, B.

AU - Aliev, M.

AU - Alimonti, G.

AU - Alison, J.

AU - Arnold, H.

AU - Da Via, C.

AU - Dao, V.

AU - Hobbs, J.

AU - Jia, J.

AU - Piacquadio, G.

AU - Tsybychev, D.

PY - 2018/7/1

Y1 - 2018/7/1

N2 - 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.].

AB - 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.].

KW - Hadron-Hadron scattering (experiments)

UR - https://www.scopus.com/pages/publications/85051260203

U2 - 10.1007/JHEP07(2018)176

DO - 10.1007/JHEP07(2018)176

M3 - Article

AN - SCOPUS:85051260203

SN - 1126-6708

VL - 2018

JO - Journal of High Energy Physics

JF - Journal of High Energy Physics

IS - 7

M1 - 176

ER -

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

Abstract

Keywords

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