Publication: Search for flavour-changing neutral-current couplings between the top quark and the photon with the ATLAS detector at & RADIC;s=13 TeV
Дата
2023
Авторы
Belotskiy, K.
Belyaev, N. L.
Bulekov, O.
Kurova, A.
Ponomarenko, D.
Proklova, N.
Pyatiizbyantseva, D.
Romaniouk, A.
Smirnov, S. Y.
Smirnov, Y.
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This letter documents a search for flavour-changing neutral currents (FCNCs), which are strongly sup-pressed in the Standard Model, in events with a photon and a top quark with the ATLAS detector. The analysis uses data collected in pp collisions at and RADIC;s =13 TeV during Run 2 of the LHC, corresponding to an integrated luminosity of 139 fb-1. Both FCNC top-quark production and decay are considered. The final state consists of a charged lepton, missing transverse momentum, a b-tagged jet, one high-momentum photon and possibly additional jets. A multiclass deep neural network is used to classify events either as signal in one of the two categories, FCNC production or decay, or as background. No significant ex-cess of events over the background prediction is observed and 95% CL upper limits are placed on the strength of left-and right-handed FCNC interactions. The 95% CL bounds on the branching fractions for the FCNC top-quark decays, estimated (expected) from both top-quark production and decay, are B(t and RARR; u and gamma; ) < 0.85 (0.88+0.37 -0.25) x 10-5 and B(t and RARR; c and gamma; ) < 4.2 (3.40+1.35-0.95) x 10-5 for a left-handed tq and gamma; cou-pling, and B(t and RARR; u and gamma; ) < 1.2 (1.20+0.50 -0.33) x10-5 and B(t and RARR; c and gamma; ) < 4.5 (3.70+1.47 -1.03) x10-5 for a right-handed coupling. and COPY; 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons .org /licenses /by /4 .0/). Funded by SCOAP3.
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Search for flavour-changing neutral-current couplings between the top quark and the photon with the ATLAS detector at & RADIC;s=13 TeV / Aad, G [et al.] // PHYSICS LETTERS B. - 2023. - 842. - 10.1016/j.physletb.2022.137379