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

G. Aad, B. Abbott, J. Abdallah, A. A. Abdelalim, A. Abdesselam, O. Abdinov, B. Abi, M. Abolins, O. S. AbouZeid, H. Abramowicz, H. Abreu, E. Acerbi, B. S. Acharya, L. Adamczyk, D. L. Adams, T. N. Addy, J. Adelman, M. Aderholz, S. Adomeit, P. AdragnaT. Adye, S. Aefsky, J. A. Aguilar-Saavedra, M. Aharrouche, S. P. Ahlen, F. Ahles, A. Ahmad, M. Ahsan, G. Aielli, T. Akdogan, T. P.A. Åkesson, G. Akimoto, A. V. Akimov, A. Akiyama, M. S. Alam, M. A. Alam, J. Albert, S. Albrand, M. Aleksa, I. N. Aleksandrov, F. Alessandria, C. Alexa, G. Alexander, G. Alexandre, T. Alexopoulos, M. Alhroob, M. Aliev, K. Kawagoe, S. Oda, J. Tojo, ATLAS Collaboration

Research output: Contribution to journalArticlepeer-review

56 Citations (Scopus)

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 √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 σqg→t×B(t→Wb)<3.9 pb. This upper limit is converted using a model-independent approach into upper limits on the coupling strengths κugt/Λ<6.9{dot operator}10-3 TeV-1 and κcgt/Λ<1.6{dot operator}10-2 TeV-1, where Λ is the new physics scale, and on the branching fractions B(t→ug)<5.7{dot operator}10-5 and B(t→cg)<2.7{dot operator}10-4.

Original languageEnglish
Pages (from-to)351-369
Number of pages19
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume712
Issue number4-5
DOIs
Publication statusPublished - Jun 12 2012

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics

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