Abstract
Abstract:
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, would be unambiguous evidence of new interactions. A dataset corresponding to
an integrated luminosity of 36.1 fb−1 of pp collisions at a center-
of-mass energy of √s = 13 TeV recorded with the ATLAS detector at the Large Hadron
Collider is used to search for top quarks decaying to up or charm quarks with the emission of a
Higgs boson, with subsequent Higgs boson decay to final states with at least one electron or muon.
No signal is observed and limits on the branching fractions B(t → Hc) < 0.16% and B(t → Hu) < 0.19%
at 95% confidence level are obtained (with expected limits of 0.15% in
both cases).