A search for the production of single top-quarks via flavour-changing neutral-currents is presented. Data collected with the ATLAS detector at a centre-of-mass energy of root s = 7 TeV, corresponding to an integrated luminosity of 2.05 fb(-1), are used. Candidate events with a semileptonic top-quark decay signature are classified as signal- or background-like events by using several kinematic variables as input to a neural network. No signal is observed in the neural network output distribution and a Bayesian upper limit is placed on the production cross-section. The observed upper limit at 95% confidence level on the cross-section multiplied by the t -> Wb branching fraction is measured to be sigma(qg -> t) x B(t -> Wb) < 3.9 pb. This upper limit is converted using a model-independent approach into upper limits on the coupling strengths kappa(ugt)/Lambda < 6.9.10(-3) TeV-1 and kappa(cgt)/Lambda < 1.6.10(-2) TeV-1, where A is the new physics scale, and on the branching fractions B(t -> ug) < 5.7.10(-5) and B(t -> cg) < 2.7.10(-4). (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.

Search for FCNC single top-quark production at √s=7 TeV with the ATLAS detector / Aad, G., Abbott, B., Abdallah, J., Abdelalim, A.A., Abdesselam, A., Abdinov, O., Abi, B., Abolins, M., Abouzeid, O.S., Abramowicz, H., Abreu, H., Acerbi, E., Acharya, B.S., Adamczyk, L., Adams, D.L., Addy, T.N., Adelman, J., Aderholz, M., Adomeit, S., Adragna, P., et al.. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - 712:4-5(2012), pp. 351-369. [10.1016/j.physletb.2012.05.022]

Search for FCNC single top-quark production at √s=7 TeV with the ATLAS detector

G. Artoni;BAGNAIA, Paolo;BINI, Cesare;DE CECCO, Sandro;DIONISI, Carlo;GENTILE, Simonetta;GIAGU, Stefano;M. Kado;LACAVA, Francesco;LUCI, Claudio;MESSINA, Andrea;MONZANI, SIMONE;A. Policicchio;SOLFAROLI CAMILLOCCI, ELENA;VANADIA, MARCO;VERDUCCI, MONICA;
2012

Abstract

A search for the production of single top-quarks via flavour-changing neutral-currents is presented. Data collected with the ATLAS detector at a centre-of-mass energy of root s = 7 TeV, corresponding to an integrated luminosity of 2.05 fb(-1), are used. Candidate events with a semileptonic top-quark decay signature are classified as signal- or background-like events by using several kinematic variables as input to a neural network. No signal is observed in the neural network output distribution and a Bayesian upper limit is placed on the production cross-section. The observed upper limit at 95% confidence level on the cross-section multiplied by the t -> Wb branching fraction is measured to be sigma(qg -> t) x B(t -> Wb) < 3.9 pb. This upper limit is converted using a model-independent approach into upper limits on the coupling strengths kappa(ugt)/Lambda < 6.9.10(-3) TeV-1 and kappa(cgt)/Lambda < 1.6.10(-2) TeV-1, where A is the new physics scale, and on the branching fractions B(t -> ug) < 5.7.10(-5) and B(t -> cg) < 2.7.10(-4). (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.
2012
single top quark; top physics; heavy-quark production; fcnc
01 Pubblicazione su rivista::01a Articolo in rivista
Search for FCNC single top-quark production at √s=7 TeV with the ATLAS detector / Aad, G., Abbott, B., Abdallah, J., Abdelalim, A.A., Abdesselam, A., Abdinov, O., Abi, B., Abolins, M., Abouzeid, O.S., Abramowicz, H., Abreu, H., Acerbi, E., Acharya, B.S., Adamczyk, L., Adams, D.L., Addy, T.N., Adelman, J., Aderholz, M., Adomeit, S., Adragna, P., et al.. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - 712:4-5(2012), pp. 351-369. [10.1016/j.physletb.2012.05.022]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/449380
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