Measurement of the total and differential cross-sections of

Measurements of inclusive and differential production cross-sections of a top-quark-top-antiquark pair in association with a boson ( ) are presented. They are performed by targeting final states with two same-sign or three isolated leptons (electrons or muons) and are based on = 13 TeV proton-proton collision data with an integrated luminosity of 140 fb 1 , recorded from 2015 to 2018 with the ATLAS detector at the Large Hadron Collider. The inclusive production cross-section is measured to be 880 80 fb, compared to a reference theoretical prediction of 745 50 (scale) 13 (2-loop approx.) 19 (PDF, ) fb. Differential cross-section measurements characterise this process in detail for the first time. Several particle-level observables are compared with a variety of theoretical predictions, which generally agree well with the normalised differential cross-section results. Additionally, the relative charge asymmetry of and is measured inclusively to be = 0.33 0.05, in very good agreement with the theoretical prediction of 0.322 0.003 (scale) 0.007 (PDF), as well as differentially.