A search for flavour changing neutral currents in top-quark decays in pp collision data collected with the ATLAS detector at sqrt(s) = 7 TeV

G. Aad , S. Albrand (1) , Q. Buat (1) , B. Clement (1) , J. Collot (1) , S. Crépé-Renaudin (1) , B. Dechenaux (1) , T. Delemontex (1) , P.A. Delsart (1) , M.H. Genest (1) , J.Y. Hostachy (1) , E. Laisne (1) , F. Ledroit-Guillon (1) , A. Lleres (1) , A. Lucotte (1) , F. Malek (1) , J. Stark (1) , X. Sun (1) , B. Trocmé (1) , J. Wang (1) , C. Weydert (1) , C. Biscarat (2) , E. Cogneras (2) , G. Rahal (2) , S. Aoun (3) , C. P. Bee (3) , C. Bertella (3) , N. Bousson (3) , J. C. Clémens (3) , Y. Coadou (3) , F. Djama (3) , F. Etienne (3) , L. Feligioni (3) , D. Hoffmann (3) , F. Hubaut (3) , E. B. F. G. Knoops (3) , E. Le Guirriec (3) , B. Li (3) , J. Maurer (3) , E. Monnier (3) , J. Odier (3) , P. Pralavorio (3) , A. Rozanov (3) , M. Talby (3) , N. Tannoury (3) , S. Tisserant (3) , J. Toth (3) , F. Touchard (3) , L. Vacavant (3) , D. Boumediene (4) , Emmanuel Busato (4) , D. Calvet (4) , S. Calvet (4) , Reina Coromoto Camacho Toro (4) , Diane Cinca (4) , J. Donini (4) , R. Febbraro (4) , N. Ghodbane (4) , C. Guicheney (4) , H. Liao (4) , D. Pallin (4) , Daniela Paredes Hernández (4) , F. Podlyski (4) , C. Santoni (4) , F. Vazeille (4) , S. Abdel Khalek (5) , H. Abreu (5) , N. Andari (5) , C. Arnault (5) , E. Augé (5) , P. Barrillon (5) , M. Benoit (5) , S. Binet (5) , C. Bourdarios (5) , C. de La Taille (5) , J.B. de Vivie de Regie (5) , L. Duflot (5) , M. Escalier (5) , L. Fayard (5) , D. Fournier (5) , J.-F. Grivaz (5) , S. Henrot-Versillé (5) , J. Hrivnac (5) , L. Iconomidou-Fayard (5) , J. Idarraga (5) , M. Kado (5) , N. Lorenzo Martinez (5) , A. Lounis (5) , N. Makovec (5) , P. Matricon (5) , F. Niedercorn (5) , L. Poggioli (5) , P. Puzo (5) , A. Renaud (5) , D. Rousseau (5) , G. Rybkin (5) , J.B. Sauvan (5) , J. Schaarschmidt (5) , A.C. Schaffer (5) , E. Scifo (5) , L. Serin (5) , S. Simion (5) , R. Tanaka (5) , M. Teinturier (5) , J.J. Veillet (5) , I. Vukotic (5) , F. Wicek (5) , D. Zerwas (5) , Zhiqing Zhang (5) , L. Aperio Bella (6) , B. Aubert (6) , N. Berger (6) , J. Colas (6) , M. Delmastro (6) , L. Di Ciaccio (6) , T.K.O. Doan (6) , S. Elles (6) , C. Goy (6) , T. Hryn'Ova (6) , A. Jérémie (6) , S. Jézéquel (6) , M. Kataoka (6) , J. Labbe (6) , R. Lafaye (6) , J. Leveque (6) , V.P. Lombardo (6) , N. Massol (6) , P. Perrodo (6) , E. Petit (6) , H. Przysiezniak (6) , E. Richter-Was (6) , G. Sauvage (6) , E. Sauvan (6) , M. Schwoerer (6) , T. Todorov (6) , D. Tsionou (6) , I. Wingerter-Seez (6) , R. Zitoun (6) , F. Vannucci (7)

1 LPSC - Laboratoire de Physique Subatomique et de Cosmologie
2 CC-IN2P3 - Centre de Calcul de l'IN2P3
3 CPPM - Centre de Physique des Particules de Marseille
4 LPC - Laboratoire de Physique Corpusculaire - Clermont-Ferrand
5 LAL - Laboratoire de l'Accélérateur Linéaire
6 LAPP - Laboratoire d'Annecy de Physique des Particules
7 APC - Neutrinos

A search for flavour changing neutral current (FCNC) processes in top-quark decays by the ATLAS Collaboration is presented. Data collected from pp collisions at the LHC at a centre-of-mass energy of sqrt(s) = 7 TeV during 2011, corresponding to an integrated luminosity of 2.1 fb^-1, were used. A search was performed for top-quark pair-production events, with one top quark decaying through the t->Zq FCNC (q=u,c) channel, and the other through the Standard Model dominant mode t->Wb. Only the decays of the Z boson to charged leptons and leptonic W-boson decays were considered as signal. Consequently, the final-state topology is characterised by the presence of three isolated charged leptons, at least two jets and missing transverse momentum from the undetected neutrino. No evidence for an FCNC signal was found. An upper limit on the t->Zq branching ratio of BR(t->Zq)<0.73% is set at the 95% confidence level.

Domaines: Physique des Hautes Energies - Expérience [hep-ex]

G. Aad, S. Albrand, Q. Buat, B. Clement, J. Collot, et al.. A search for flavour changing neutral currents in top-quark decays in pp collision data collected with the ATLAS detector at sqrt(s) = 7 TeV. Journal of High Energy Physics, 2012, 09 (2012), pp.139. ⟨10.1007/JHEP09(2012)139⟩. ⟨in2p3-00703608⟩