Search for flavour-changing neutral-current couplings between the top quark and the photon with the ATLAS detector at s=13 TeV

The ATLAS collaboration

doi:10.1016/j.physletb.2022.137379

Search for flavour-changing neutral-current couplings between the top quark and the photon with the ATLAS detector at s=13 TeV

The ATLAS collaboration

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

12 Scopus citations

Abstract

This letter documents a search for flavour-changing neutral currents (FCNCs), which are strongly suppressed in the Standard Model, in events with a photon and a top quark with the ATLAS detector. The analysis uses data collected in pp collisions at s=13 TeV during Run 2 of the LHC, corresponding to an integrated luminosity of 139 fb⁻¹. Both FCNC top-quark production and decay are considered. The final state consists of a charged lepton, missing transverse momentum, a b-tagged jet, one high-momentum photon and possibly additional jets. A multiclass deep neural network is used to classify events either as signal in one of the two categories, FCNC production or decay, or as background. No significant excess of events over the background prediction is observed and 95% CL upper limits are placed on the strength of left- and right-handed FCNC interactions. The 95% CL bounds on the branching fractions for the FCNC top-quark decays, estimated (expected) from both top-quark production and decay, are B(t→uγ)<0.85(0.88_−0.25 ^+0.37)×10⁻⁵ and B(t→cγ)<4.2(3.40_−0.95 ^+1.35)×10⁻⁵ for a left-handed tqγ coupling, and B(t→uγ)<1.2(1.20_−0.33 ^+0.50)×10⁻⁵ and B(t→cγ)<4.5(3.70_−1.03 ^+1.47)×10⁻⁵ for a right-handed coupling.

Original language	English
Article number	137379
Journal	Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume	842
DOIs	https://doi.org/10.1016/j.physletb.2022.137379
State	Published - 10 Jul 2023

Funding

Funders	Funder number
CEA-DRF
Canton of Bern and Geneva
DNSRC	IN2P3-CNRS
EU-ESF
GenT Programmes Generalitat Valenciana , Spain
GenT Programmes Generalitat Valenciana, Spain
GridKA
INFN-CNAF
La Caixa Banking Foundation
MIZŠ
MNE
NDGF	CC-IN2P3
Norwegian Financial Mechanism	2014-2021
PROMETEO
RGC
UNCE	SCI/013
Wallenberg Foundation
National Science Foundation
U.S. Department of Energy
Alexander von Humboldt-Stiftung
Alabama Space Grant Consortium
Brookhaven National Laboratory
Karlsruhe Institute of Technology
H2020 Marie Skłodowska-Curie Actions
Multiple Sclerosis Scientific Research Foundation
CERN
Göran Gustafssons Stiftelser
Natural Sciences and Engineering Research Council of Canada
National Research Council Canada
Canada Foundation for Innovation
Science and Technology Facilities Council
Leverhulme Trust
European Research Council
European Cooperation in Science and Technology
Australian Research Council
National Stroke Foundation
Neurosurgical Research Foundation
Helmholtz-Gemeinschaft
Minerva Foundation
Deutsche Forschungsgemeinschaft
Agence Nationale de la Recherche
Japan Society for the Promotion of Science
Ministry of Education, Culture, Sports, Science and Technology
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
Danmarks Grundforskningsfond
Fundação de Amparo à Pesquisa do Estado de São Paulo
National Natural Science Foundation of China
Ministerstvo Školství, Mládeže a Tělovýchovy
Fundação para a Ciência e a Tecnologia
Bundesministerium für Bildung und Forschung
Chinese Academy of Sciences
Austrian Science Fund
Generalitat de Catalunya
Ministry of Science and Technology of the People's Republic of China
Agencia Nacional de Promoción Científica y Tecnológica
Nederlandse Organisatie voor Wetenschappelijk Onderzoek
Bundesministerium für Wissenschaft, Forschung und Wirtschaft
Conselho Nacional de Desenvolvimento Científico e Tecnológico
Nella and Leon Benoziyo Center for Neurological Diseases, Weizmann Institute of Science
Israel Science Foundation
Instituto Nazionale di Fisica Nucleare
Narodowe Centrum Nauki
Javna Agencija za Raziskovalno Dejavnost RS
Ministarstvo Prosvete, Nauke i Tehnološkog Razvoja
Ministerio de Ciencia e Innovación
Centre National pour la Recherche Scientifique et Technique
Staatssekretariat für Bildung, Forschung und Innovation
Horizon 2020
British Columbia Knowledge Development Fund	21/SCI/017
European Regional Development Fund
Defence Science Institute
Narodowa Agencja Wymiany Akademickiej
Institutul de Fizică Atomică
Agencia Nacional de Investigación y Desarrollo
Royal Society of South Australia
Irish Rugby Football Union

Access to Document

10.1016/j.physletb.2022.137379

Cite this

@article{8f01db942dd645caa1e11d72124dbe2c,

title = "Search for flavour-changing neutral-current couplings between the top quark and the photon with the ATLAS detector at s=13 TeV",

abstract = "This letter documents a search for flavour-changing neutral currents (FCNCs), which are strongly suppressed in the Standard Model, in events with a photon and a top quark with the ATLAS detector. The analysis uses data collected in pp collisions at s=13 TeV during Run 2 of the LHC, corresponding to an integrated luminosity of 139 fb−1. Both FCNC top-quark production and decay are considered. The final state consists of a charged lepton, missing transverse momentum, a b-tagged jet, one high-momentum photon and possibly additional jets. A multiclass deep neural network is used to classify events either as signal in one of the two categories, FCNC production or decay, or as background. No significant excess of events over the background prediction is observed and 95% CL upper limits are placed on the strength of left- and right-handed FCNC interactions. The 95% CL bounds on the branching fractions for the FCNC top-quark decays, estimated (expected) from both top-quark production and decay, are B(t→uγ)<0.85(0.88−0.25 +0.37)×10−5 and B(t→cγ)<4.2(3.40−0.95 +1.35)×10−5 for a left-handed tqγ coupling, and B(t→uγ)<1.2(1.20−0.33 +0.50)×10−5 and B(t→cγ)<4.5(3.70−1.03 +1.47)×10−5 for a right-handed coupling.",

author = "{The ATLAS collaboration} and G. Aad and B. Abbott and Abbott, {D. C.} and O. Abdinov and Abud, {A. Abed} and K. Abeling and Abhayasinghe, {D. K.} 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 B. Achkar and S. Adachi and L. Adam and Bourdarios, {C. Adam} and L. Adamczyk and L. Adamek and J. Adelman and M. Adersberger and A. Adiguzel and S. Adorni and T. Adye and Affolder, {A. A.} and Y. Afik and C. Agapopoulou and Agaras, {M. N.} and A. Aggarwal and C. Agheorghiesei and Aguilar-Saavedra, {J. A.} and L. Barak and G. Bella and Y. Benhammou and Biswal, {J. P.} and T. Cao and B. Chen and H. Cohen and E. Etzion and G. Koren and O. Kuprash and Lutz, {M. S.} and Y. Oren and Dominguez, {L. Pascual} and M. Pitt and D. Reikher and A. Soffer and Tamir, {N. M.} and D. Vannicola",

note = "Publisher Copyright: {\textcopyright} 2022 The Author(s)",

year = "2023",

month = jul,

day = "10",

doi = "10.1016/j.physletb.2022.137379",

language = "אנגלית",

volume = "842",

journal = "Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics",

issn = "0370-2693",

publisher = "Elsevier B.V.",

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TY - JOUR

T1 - Search for flavour-changing neutral-current couplings between the top quark and the photon with the ATLAS detector at s=13 TeV

AU - The ATLAS collaboration

AU - Aad, G.

AU - Abbott, B.

AU - Abbott, D. C.

AU - Abdinov, O.

AU - Abud, A. Abed

AU - Abeling, K.

AU - Abhayasinghe, D. K.

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 - Achkar, B.

AU - Adachi, S.

AU - Adam, L.

AU - Bourdarios, C. Adam

AU - Adamczyk, L.

AU - Adamek, L.

AU - Adelman, J.

AU - Adersberger, M.

AU - Adiguzel, A.

AU - Adorni, S.

AU - Adye, T.

AU - Affolder, A. A.

AU - Afik, Y.

AU - Agapopoulou, C.

AU - Agaras, M. N.

AU - Aggarwal, A.

AU - Agheorghiesei, C.

AU - Aguilar-Saavedra, J. A.

AU - Barak, L.

AU - Bella, G.

AU - Benhammou, Y.

AU - Biswal, J. P.

AU - Cao, T.

AU - Chen, B.

AU - Cohen, H.

AU - Etzion, E.

AU - Koren, G.

AU - Kuprash, O.

AU - Lutz, M. S.

AU - Oren, Y.

AU - Dominguez, L. Pascual

AU - Pitt, M.

AU - Reikher, D.

AU - Soffer, A.

AU - Tamir, N. M.

AU - Vannicola, D.

PY - 2023/7/10

Y1 - 2023/7/10

N2 - This letter documents a search for flavour-changing neutral currents (FCNCs), which are strongly suppressed in the Standard Model, in events with a photon and a top quark with the ATLAS detector. The analysis uses data collected in pp collisions at s=13 TeV during Run 2 of the LHC, corresponding to an integrated luminosity of 139 fb−1. Both FCNC top-quark production and decay are considered. The final state consists of a charged lepton, missing transverse momentum, a b-tagged jet, one high-momentum photon and possibly additional jets. A multiclass deep neural network is used to classify events either as signal in one of the two categories, FCNC production or decay, or as background. No significant excess of events over the background prediction is observed and 95% CL upper limits are placed on the strength of left- and right-handed FCNC interactions. The 95% CL bounds on the branching fractions for the FCNC top-quark decays, estimated (expected) from both top-quark production and decay, are B(t→uγ)<0.85(0.88−0.25 +0.37)×10−5 and B(t→cγ)<4.2(3.40−0.95 +1.35)×10−5 for a left-handed tqγ coupling, and B(t→uγ)<1.2(1.20−0.33 +0.50)×10−5 and B(t→cγ)<4.5(3.70−1.03 +1.47)×10−5 for a right-handed coupling.

AB - This letter documents a search for flavour-changing neutral currents (FCNCs), which are strongly suppressed in the Standard Model, in events with a photon and a top quark with the ATLAS detector. The analysis uses data collected in pp collisions at s=13 TeV during Run 2 of the LHC, corresponding to an integrated luminosity of 139 fb−1. Both FCNC top-quark production and decay are considered. The final state consists of a charged lepton, missing transverse momentum, a b-tagged jet, one high-momentum photon and possibly additional jets. A multiclass deep neural network is used to classify events either as signal in one of the two categories, FCNC production or decay, or as background. No significant excess of events over the background prediction is observed and 95% CL upper limits are placed on the strength of left- and right-handed FCNC interactions. The 95% CL bounds on the branching fractions for the FCNC top-quark decays, estimated (expected) from both top-quark production and decay, are B(t→uγ)<0.85(0.88−0.25 +0.37)×10−5 and B(t→cγ)<4.2(3.40−0.95 +1.35)×10−5 for a left-handed tqγ coupling, and B(t→uγ)<1.2(1.20−0.33 +0.50)×10−5 and B(t→cγ)<4.5(3.70−1.03 +1.47)×10−5 for a right-handed coupling.

UR - http://www.scopus.com/inward/record.url?scp=85146929561&partnerID=8YFLogxK

U2 - 10.1016/j.physletb.2022.137379

DO - 10.1016/j.physletb.2022.137379

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AN - SCOPUS:85146929561

SN - 0370-2693

VL - 842

JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

M1 - 137379

ER -

Search for flavour-changing neutral-current couplings between the top quark and the photon with the ATLAS detector at s=13 TeV

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