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

abstract

  • 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 $$ sqrt{s}=13 $$ s = 13 TeV, corresponding to an integrated luminosity of 36.1 fb1, 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 1.7 104 (2.4 104) on the t uZ branching ratio and 2.4 104 (3.2 104) on the t cZ branching ratio, constituting the most stringent limits to date.

altmetric score

  • 0.25

author list (cited authors)

  • Aaboud, M., Aad, G., Abbott, B., Abdinov, O., Abeloos, B., Abidi, S. H., ... Zwalinski, L.

citation count

  • 19

complete list of authors

  • 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||Ante