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 root s = 13TeV, 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 x 10(-4) (2.4 x 10(-4)) on the t -> uZ branching ratio and 2.4 x 10(-4) (3.2 x 10(-4)) on the t -> cZ branching ratio, constituting the most stringent limits to date.

Search for flavour-changing neutral current top-quark decays t -> qZ in proton-proton collisions at root s=13 TeV with the ATLAS detector / Aaboud, M., Aad, G., Abbott, B., Abdinov, O., Abeloos, B., Abidi, S.H., Abouzeid, O.S., Abraham, N.L., Abramowicz, H., Abreu, H., Abulaiti, Y., Acharya, B.S., Adachi, S., Adamczyk, L., Adelman, J., Adersberger, M., Adye, T., Affolder, A.A., Afik, Y., Agheorghiesei, C., et al.. - In: JOURNAL OF HIGH ENERGY PHYSICS. - ISSN 1029-8479. - 7(2018). [10.1007/JHEP07(2018)176]

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

Bagnaia, P.;Bini, C.;De Cecco, S.;Gentile, S.;Giagu, S.;Kado, M.;Lacava, F.;Luci, C.;Messina, A.;Policicchio, A.;
2018

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 root s = 13TeV, 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 x 10(-4) (2.4 x 10(-4)) on the t -> uZ branching ratio and 2.4 x 10(-4) (3.2 x 10(-4)) on the t -> cZ branching ratio, constituting the most stringent limits to date.
2018
Hadron-Hadron scattering (experiments); PARTON DISTRIBUTIONS; PLUS PLUS; HADRON COLLIDERS; PAIR-PRODUCTION; CROSS-SECTION; HERWIG PLUS; LHC; PHYSICS; MODELS; LEP
01 Pubblicazione su rivista::01a Articolo in rivista
Search for flavour-changing neutral current top-quark decays t -> qZ in proton-proton collisions at root s=13 TeV with the ATLAS detector / Aaboud, M., Aad, G., Abbott, B., Abdinov, O., Abeloos, B., Abidi, S.H., Abouzeid, O.S., Abraham, N.L., Abramowicz, H., Abreu, H., Abulaiti, Y., Acharya, B.S., Adachi, S., Adamczyk, L., Adelman, J., Adersberger, M., Adye, T., Affolder, A.A., Afik, Y., Agheorghiesei, C., et al.. - In: JOURNAL OF HIGH ENERGY PHYSICS. - ISSN 1029-8479. - 7(2018). [10.1007/JHEP07(2018)176]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1212609
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