Search for Flavour-Changing Neutral Current Top-Quark Decays to qZ in pp Collision Data Collected with the ATLAS Detector at √s̅ = 8 TeV


A search for the flavour-changing neutral-current decay t → qZ is presented. Data collected by the ATLAS detector during 2012 from proton-proton collisions at the Large Hadron Collider at a centre-of-mass energy of √s̅ = 8 TeV, corresponding to an integrated luminosity of 20.3 fb⁻¹, are analysed. Top-quark pair-production events with one top quark decaying through the t → qZ (q=u,c) channel and the other through the dominant Standard Model mode t → bW are considered as signal. Only the decays of the Z boson to charged leptons and leptonic W boson decays are used. No evidence for a signal is found and an observed (expected) upper limit on the t → qZ branching ratio of 7 x 10⁻⁴ (8 x 10⁻⁴) is set at the 95% confidence level



Z bosons, Jets (Nuclear physics), W bosons, Leptons (Nuclear physics), Top Quarks, Transverse momentum


CC BY 4.0 (Attribution), ©2016 CERN, for the ATLAS Collaboration