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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

  • Author(s): Aaboud, M
  • Aad, G
  • Abbott, B
  • Abdinov, O
  • Abeloos, B
  • Abidi, SH
  • AbouZeid, OS
  • Abraham, NL
  • Abramowicz, H
  • Abreu, H
  • Abulaiti, Y
  • Acharya, BS
  • Adachi, S
  • Adamczyk, L
  • Adelman, J
  • Adersberger, M
  • Adye, T
  • Affolder, AA
  • Afik, Y
  • Agheorghiesei, C
  • Aguilar-Saavedra, JA
  • Ahmadov, F
  • Aielli, G
  • Akatsuka, S
  • Akerstedt, H
  • Åkesson, TPA
  • Akilli, E
  • Akimov, AV
  • Alberghi, GL
  • Albert, J
  • Albicocco, P
  • Alconada Verzini, MJ
  • Alderweireldt, S
  • Aleksa, M
  • Aleksandrov, IN
  • Alexa, C
  • Alexander, G
  • Alexopoulos, T
  • Alhroob, M
  • Ali, B
  • Aliev, M
  • Alimonti, G
  • Alison, J
  • Alkire, SP
  • Allaire, C
  • Allbrooke, BMM
  • Allen, BW
  • Allport, PP
  • Aloisio, A
  • Alonso, A
  • Alonso, F
  • Alpigiani, C
  • Alshehri, AA
  • Alstaty, MI
  • Alvarez Gonzalez, B
  • Álvarez Piqueras, D
  • Alviggi, MG
  • Amadio, BT
  • Amaral Coutinho, Y
  • Amelung, C
  • Amidei, D
  • Amor Dos Santos, SP
  • Amoroso, S
  • Anastopoulos, C
  • Ancu, LS
  • Andari, N
  • Andeen, T
  • Anders, CF
  • Anders, JK
  • Anderson, KJ
  • Andreazza, A
  • Andrei, V
  • Angelidakis, S
  • Angelozzi, I
  • Angerami, A
  • Anisenkov, AV
  • Annovi, A
  • Antel, C
  • Antonelli, M
  • Antonov, A
  • Antrim, DJA
  • Anulli, F
  • Aoki, M
  • Aperio Bella, L
  • Arabidze, G
  • Arai, Y
  • et al.

Published Web Location

http://doi.org/10.1007/JHEP07(2018)176
No data is associated with this publication.
Abstract

© 2018, The Author(s). 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.].

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