First Run 3 data/MC plots for the measurement of the top-quark pair production cross-section in pp collisions at centre-of-mass energy of 13.6 TeV with the ATLAS experiment at the LHC
The top quark is the heaviest known elementary particle. Its large mass, close to the scale of electroweak symmetry breaking, hints at a unique role in the Standard Model of particle physics. The study of top quark-antiquark ($t\bar{t}$) production is an important part of the physics programme of the ATLAS experiment at the CERN Large Hadron Collider (LHC). It allows quantum chromodynamics to be probed at some of the highest reachable energy scales. The $t\bar{t}$ production also forms a crucial background in many searches for physics beyond the Standard Model. Therefore, precise measurements the $t\bar{t}$ process are essential to fully exploit the discovery potential of the LHC. A comparison of data and prediction in the electron-muon final state is presented, aiming to reconstruct $t\bar{t}$ events. Data are collected in the period F1 of the LHC Run 3 at the centre-of-mass of 13.6 TeV, during the first week of August 2022, corresponding to an integrated luminosity of about 790 pb$^{-1}$.