Measurement of the tt̄Z and tt̄W production cross sections in multilepton final states using 3.2 fb^-1 of pp collisions at √s = 13 TeV with the ATLAS detector 

A measurement of the tt̄W and tt̄W production cross sections in final states with either two same-charge muons, or three or four leptons (electrons or muons) is presented. The analysis uses a data sample of proton–proton collisions at √s =13 TeV recorded with the ATLAS detector at the Large Hadron Collider in 2015, corresponding to a total integrated luminosity of 3.2 fb⁻¹. The inclusive cross sections are extracted using likelihood fits to signal and control regions, resulting in σ_tt̄Z=0.9±0.3 pb and σ_tt̄W=1.5±0.8 pb, in agreement with the Standard Model predictions.