Search for flavour-changing neutral current top-quark decays to $qZ$ in $pp$ collision data collected with the ATLAS detector at $\sqrt{s}=8$ TeV

G. Aad 1 Z. Barnovska 2 N. Berger 2 M. Delmastro 2 L. Di Ciaccio 2 T.K.O. Doan 2 S. Elles 2 C. Goy 2 T. Hryn’ova 2 S. Jézéquel 2 I. Koletsou 2 R. Lafaye 2 J. Leveque 2 N. Massol 2 G. Sauvage 2 E. Sauvan 2 O. Simard 2 T. Todorov 2 I. Wingerter-Seez 2 G . Rahal 3 D. Boumediene 4 Emmanuel Busato 4 D. Calvet 4 S. Calvet 4 J. Donini 4 E. Dubreuil 4 G. Gilles 4 Ph. Gris 4 H. Liao 4 R. Madar 4 D. Pallin 4 S.M. Romano Saez 4 C. Santoni 4 D. Simon 4 Timothée Theveneaux-Pelzer 4 F. Vazeille 4 S. Albrand 5 J. Brown 5 J. Collot 5 S. Crépé-Renaudin 5 P.A. Delsart 5 C. Gabaldon 5 M.H. Genest 5 J.Y. Hostachy 5 F. Ledroit-Guillon 5 A. Lleres 5 A. Lucotte 5 F. Malek 5 C. Monini 5 J. Stark 5 B. Trocmé 5 M. Wu 5 L. Alio 1 M. Barbero 1 Y. Coadou 1 C. Diaconu 1 S. Diglio 1 F. Djama 1 O. Duccu 1, 6 L. Feligioni 1 J. Gao 1 G.D. Hallewell 1 F. Hubaut 1 S.J. Kahn E. B. F. G. Knoops 1 E. Le Guirriec 1 J. Liu 1 K. Liu 1 D. Madaffari 1 K. Mochizuki 1 E. Monnier 1 S. Muanza 1 Y. Nagai 1 E. Nagy 1 P. Pralavorio 1 A. Rozanov 1 T. Serre 1 M. Talby 1 R.E. Ticse Torres 1 E. Tiouchichine 1 S. Tisserant 1 J. Toth 1 F. Touchard 1 L. Vacavant 1 M.K. Ayoub 7 A. Bassalat 7 C. Bécot 7 S. Binet 7 C. Bourdarios 7 D. Delgove 7 J-B. de Vivie De Regie 7 L. Duflot 7 M. Escalier 7 L. Fayard 7 D. Fournier 7 E.L. Gkougkousis 7 J-F. Grivaz 7 T. Guillemin 7 F. Hariri 7 S. Henrot-Versille 7 J. Hrivnac 7 L. Iconomidou-Fayard 7 M. Kado 7 A. Lounis 7 N. Makovec 7 N. Morange 7 C. Nellist 7 P. Petroff 7 L. Poggioli 7 P. Puzo 7 A. Renaud 7 D. Rousseau 7 G. Rybkin 7 A.C. Schaffer 7 E. Scifo 7 L. Serin 7 S. Simion 7 R. Tanaka 7 D. Zerwas 7 Zhongkai Zhang 7 Y. Zhao 7 E. Yatsenko 2
Abstract : A search for the flavour-changing neutral-current decay $t\to qZ$ is presented. Data collected by the ATLAS detector during 2012 from proton-proton collisions at the Large Hadron Collider at a centre-of-mass energy of $\sqrt{s}=8$ TeV, corresponding to an integrated luminosity of 20.3 fb$^{-1}$, are analysed. Top-quark pair-production events with one top quark decaying through the $t\to qZ$ ($q=u,c$) channel and the other through the dominant Standard Model mode $t\to bW$ are considered as signal. Only the decays of the $Z$ boson to charged leptons and leptonic $W$ boson decays are used. No evidence for a signal is found and an observed (expected) upper limit on the $t\to qZ$ branching ratio of $7\times 10^{-4}$ ($8\times 10^{-4}$) is set at the 95% confidence level.
Type de document :
Article dans une revue
European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2016, 76, pp.12. 〈10.1140/epjc/s10052-015-3851-5〉
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Soumis le : mardi 25 août 2015 - 11:36:43
Dernière modification le : mardi 13 février 2018 - 13:28:06

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G. Aad, Z. Barnovska, N. Berger, M. Delmastro, L. Di Ciaccio, et al.. Search for flavour-changing neutral current top-quark decays to $qZ$ in $pp$ collision data collected with the ATLAS detector at $\sqrt{s}=8$ TeV. European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2016, 76, pp.12. 〈10.1140/epjc/s10052-015-3851-5〉. 〈in2p3-01186567〉

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