Search for flavour-changing neutral currents in processes with one top quark and a photon using 81 fb-1 of pp collisions at with the ATLAS experiment
A search for flavour-changing neutral current (FCNC) events via the coupling of a top quark, a photon, and an up or charm quark is presented using 81 fb-1 of proton–proton collision data taken at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. Events with a photon, an electron or muon, a b-tagged jet, and missing transverse momentum are selected. A neural network based on kinematic variables differentiates between events from signal and background processes. The data are consistent with the background-only hypothesis, and limits are set on the strength of the tqγ coupling in an effective field theory. These are also interpreted as 95% CL upper limits on the cross section for FCNC tγ production via a left-handed (right-handed) tuγ coupling of 36 fb (78 fb) and on the branching ratio for t→γu of 2.8×10-5 (6.1×10-5). In addition, they are interpreted as 95% CL upper limits on the cross section for FCNC tγ production via a left-handed (right-handed) tcγ coupling of 40 fb (33 fb) and on the branching ratio for t→γc of 22×10-5 (18×10-5).
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of Oregon, Eugene, OR (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Harvard Univ., Cambridge, MA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), High Energy Physics (HEP)
- Contributing Organization:
- The ATLAS Collaboration
- Grant/Contract Number:
- AC02-05CH11231; SC0017996; AC02-76SF00515; SC0007881
- OSTI ID:
- 1575102
- Alternate ID(s):
- OSTI ID: 1582634; OSTI ID: 1597116; OSTI ID: 1633997; OSTI ID: 1706085
- Journal Information:
- Physics Letters B, Journal Name: Physics Letters B Vol. 800 Journal Issue: C; ISSN 0370-2693
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- Netherlands
- Language:
- English
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