Search for flavour-changing neutral currents $tZ$ interactions in $pp$ collisions at $\sqrt{s}$=13~TeV with ATLAS

A search for the flavour-changing neutral $tqZ$ vertex in trilepton events in proton-proton collisions at a centre-of-mass energy of 13 TeV with the ATLAS detector at the CERN Large Hadron Collider is presented. The analysed data corresponds to an integrated luminosity of 36.1 $fb^{-1}$. The analysis is performed on events with three isolated electrons or muons, including the mixed cases, missing transverse momentum and exactly one $b$-tagged jet in the final state. Exclusion limits for the branching ratios on the $t\to qZ$ processes are given and interpreted in the framework of an effective field theory in the top quark sector.