Search for the SM four-top-quark production in $pp$ collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector

Recently the ATLAS Collaboration carried out two searches for the Standard Model four-top-quark production in the single-lepton and opposite-sign dilepton channel, and in the same-sign dilepton and multilepton channels. The searches are based on a dataset of $pp$ collisions at $\sqrt{s} = 13$ TeV recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider and corresponds to an integrated luminosity of $36.1$ fb$^{-1}$. No significant excess above the Standard Model expectation is observed in either of the two searches. The results are combined and an observed (expected) upper limit of 49 fb (19 fb), or 5.3 (2.1) times the four-top-quark Standard Model cross section is obtained at 95% confidence level.