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 (Formula presented.) 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 (Formula presented.) branching fraction is set. The observed 95 % CL limit is (Formula presented.) and the expected 95 % CL limit is (Formula presented.). 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 (Formula presented.) and (Formula presented.) and on the branching fractions (Formula presented.) and (Formula presented.).

Search for single top-quark production via flavour-changing neutral currents at 8 TeV with the ATLAS detector

CAVASINNI, VINCENZO;DELL'ORSO, MAURO;DONATI, SIMONE;Francavilla, P.;RODA, CHIARA MARIA ANGELA;Verducci, M.;
2016-01-01

Abstract

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 (Formula presented.) 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 (Formula presented.) branching fraction is set. The observed 95 % CL limit is (Formula presented.) and the expected 95 % CL limit is (Formula presented.). 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 (Formula presented.) and (Formula presented.) and on the branching fractions (Formula presented.) and (Formula presented.).
2016
Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Aben, R.; Abolins, M.; Abouzeid, O. S.; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/826148
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