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

School of Physics and Astronomy

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
Faculté des Sciences
Mohamed I University
Aix-Marseille Université
University of Oklahoma
Azerbaijan National Academy of Sciences
Université Paris-Sud
University of Toronto
University of California at Santa Cruz
University of Sussex
Physics Department
Technion-Israel Institute of Technology
Department of Physics
Stockholm University
Oskar Klein Centre
National Institute for Nuclear Physics
Abdus Salam International Centre for Theoretical Physics
King's College London
International Center for Elementary Particle Physics and Department of Physics
The University of Tokyo
Faculty of Physics and Applied Computer Science
AGH University of Krakow
Department of Physics
Northern Illinois University
Fakultät für Physik
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
Departamento de Física Teórica y del Cosmos
University of Granada
Joint Institute for Nuclear Research
University of Rome Tor Vergata
Kyoto University
Fysiska institutionen
Lund University
Département de Physique Nucléaire et Corpusculaire
University of Geneva
RAS - P.N. Lebedev Physics Institute
University of Bologna
Department of Physics and Astronomy
University of Victoria BC
Universidad Nacional de La Plata
Institute for Mathematics
Radboud University Nijmegen
Department of Physics
Alexandru Ioan Cuza University of Iaşi
Physics Department
National Technical University of Athens
University of Massachusetts
Weizmann Institute of Science

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

55 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 - 1 Jul 2018

Funding

Funders	Funder number
Departamento Administrativo de Ciencia, Tecnología e Innovación (COLCIENCIAS)
Agence Nationale de la Recherche
Australian Research Council
Centre National pour la Recherche Scientifique et Technique
Fundação para a Ciência e a Tecnologia
Comisión Nacional de Investigación Científica y Tecnológica
Narodowe Centrum Nauki
CEA-DRF
Région Auvergne
Nederlandse Organisatie voor Wetenschappelijk Onderzoek
Ministry of Science and Technology, Taiwan
Israel Science Foundation
Wallenberg Foundation
Arizona-Nevada Academy of Science
Javna Agencija za Raziskovalno Dejavnost RS
Instituto Nazionale di Fisica Nucleare
Bundesministerium für Wissenschaft, Forschung und Wirtschaft
Austrian Science Fund
Department of Science and Technology, Ministry of Science and Technology, India
MSMT
MSSR
Marie Sklo dowska-Curie Actions
Ministerio de Economía y Competitividad
Bundesministerium für Bildung und Forschung
Canada Foundation for Innovation
Helmholtz-Gemeinschaft
Danmarks Grundforskningsfond
Conselho Nacional de Desenvolvimento Científico e Tecnológico
Czech Republic
Singapore Eye Research Institute
Canarie
Ontario Innovation Trust
Deutsche Forschungsgemeinschaft
European Commission
Neurosurgical Research Foundation
MESTD
U.S. Department of Energy
RGC
Fundação de Amparo à Pesquisa do Estado de São Paulo
Israeli Centers for Research Excellence
MES of Russia
National Research Center "Kurchatov Institute"
Institutul de Fizică Atomică
Natural Sciences and Engineering Research Council of Canada
General Secretariat for Research and Technology
Nella and Leon Benoziyo Center for Neurological Diseases, Weizmann Institute of Science
Thales and Aristeia
Fonds Québécois de la Recherche sur la Nature et les Technologies
Cantons of Bern and Geneva
Canada Council for the Arts
Chinese Academy of Sciences
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
VSC CR
CRC Health Group
Compute Canada
MNE
Agencia Nacional de Promoción Científica y Tecnológica
European Research Council
European Regional Development Fund
Ministerstwo Nauki i Szkolnictwa Wyższego
IRFU
CERN
Joint Institute for Nuclear Research
Fondation Partager le Savoir
In-vestissements d’Avenir Labex
National Research Council Canada
Alexander von Humboldt-Stiftung
Council on grants of the President of the Russian Federation
Horizon 2020
British Columbia Knowledge Development Fund
Ministry of Education, Culture, Sports, Science and Technology
National Natural Science Foundation of China
???publication-publication-funding-organisation-not-added???	ST/J005533/1, ST/L006162/1, ST/N000447/1, ST/J004804/1, ST/N000307/1, ST/M000753/1, ST/L003449/1, ST/K001329/1, ST/N000420/1
National Science Foundation	1812377, 1624739
Japan Society for the Promotion of Science	16H06493
DNSRC	IN2P3-CNRS

Keywords

Hadron-Hadron scattering (experiments)

Access to Document

10.1007/JHEP07(2018)176

Cite this

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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 {\texttimes} 10−4 (2.4 {\texttimes} 10−4) on the t → uZ branching ratio and 2.4 {\texttimes} 10−4 (3.2 {\texttimes} 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 A. Ashkenazi and L. Barak and G. Bella and Y. Benhammou and T. Cao and E. Etzion and O. Kuprash and Lutz, \{M. S.\} and Y. Oren and M. Pitt and A. Soffer",

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

year = "2018",

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

language = "אנגלית",

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journal = "Journal of High Energy Physics",

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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 - Ashkenazi, A.

AU - Barak, L.

AU - Bella, G.

AU - Benhammou, Y.

AU - Cao, T.

AU - Etzion, E.

AU - Kuprash, O.

AU - Lutz, M. S.

AU - Oren, Y.

AU - Pitt, M.

AU - Soffer, A.

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)

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U2 - 10.1007/JHEP07(2018)176

DO - 10.1007/JHEP07(2018)176

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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

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Funding

Keywords

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