Measurement of four-top-quarks production with the ATLAS Detector

A search for four-top-quark production using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the ATLAS detector corresponding to an integrated luminosity of 139 fb^{−1} for the same-sign lepton pair or at least three leptons and 36 fb^{−1} for the single-lepton and opposite-sign dilepton channels. In the multilepton final states, the four-top-quark production cross section is measured to be 24^{+7}_{−6} fb, corresponding to an observed (expected) signal significance of 4.3 (2.4) standard deviations and providing evidence for this process.