Search for flavor-changing neutral currents in top quark decays t →hc and t →hu in multilepton final states in proton-proton collisions at s =13 TeV with the ATLAS detector
Flavor-changing neutral currents are not present in the Standard Model at tree level and are suppressed in loop processes by the unitarity of the Cabibbo-Kobayashi-Maskawa matrix; the corresponding rates for top quark decay processes are experimentally unobservable. Extensions of the Standard Model can generate new flavor-changing neutral current processes, leading to signals which, if observed, w