Search for single top-quark production via flavour-changing neutral currents at 8 TeV with the ATLAS detector
A search for single top-quark production via flavour-changing neutral current processes from gluon plus up- or charm-quark initial states in proton–proton collisions at the LHC is presented. Data collected with the ATLAS detector in 2012 at a centre-of-mass energy of 8 TeV and corresponding to an in...
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| Format: | Article |
| Language: | en_US |
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Springer-Verlag
2017
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| Online Access: | http://hdl.handle.net/1721.1/106548 https://orcid.org/0000-0002-7586-7253 |
| Summary: | A search for single top-quark production via flavour-changing neutral current processes from gluon plus up- or charm-quark initial states in proton–proton collisions at the LHC is presented. Data collected with the ATLAS detector in 2012 at a centre-of-mass energy of 8 TeV and corresponding to an integrated luminosity of 20.3 fb[superscript −1] are used. Candidate events for a top quark decaying into a lepton, a neutrino and a jet are selected and classified into signal- and background-like candidates using a neural network. No signal is observed and an upper limit on the production cross-section multiplied by the t→Wb branching fraction is set. The observed 95 % CL limit is σ[subscript qg→t]×B(t→Wb)<3.4 pb and the expected 95 % CL limit is σ[subscript qg]→t×B(t→Wb)<2.9 pb. The observed limit can be interpreted as upper limits on the coupling constants of the flavour-changing neutral current interactions divided by the scale of new physics κ[subscript ugt]/Λ<5.8×10[superscript −3] TeV[superscript −1] and κ[subscrip cgt]/Λ<13×10[superscript −3] TeV and on the branching fractions B(t→ug)<4.0×10[superscript −5] and B(t→cg)<20×10[superscript −5] . |
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