Search for FCNC single top-quark production at √s = 7 TeV with the ATLAS detector
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[superscript −1], are used. Candidate events with a semileptonic t...
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| Format: | Article |
| Language: | en_US |
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Elsevier
2014
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| Online Access: | http://hdl.handle.net/1721.1/92027 https://orcid.org/0000-0002-7586-7253 |
| Summary: | 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[superscript −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 σ[subscript qg→t]×B(t→Wb)<3.9 pb. This upper limit is converted using a model-independent approach into upper limits on the coupling strengths κ[subscript ugt]/Λ<6.9⋅10[superscript −3] TeV[superscript −1] and κ[subscript cgt]/Λ<1.6⋅10[superscript −2] TeV[superscript −1], where Λ is the new physics scale, and on the branching fractions B(t→ug)<5.7⋅10[superscript −5] and B(t→cg)<2.7⋅10[superscript −4]. |
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