Search for standard model production of four top quarks in proton-proton collisions at 13 TeV

A search for standard model four top quark production, combining the single lepton and dilepton channels, is presented. The analysis utilises the data recorded by the CMS experiment at $\sqrt{s} = 13~$TeV in 2015, which corresponds to an integrated luminosity of 2.6 ${\mathrm{fb^{-1}}}$. A boosted decision tree algorithm is used to select signal and suppress background events. Upper limits on four top quark production of $10.2 \times \sigma_{t\overline{t}t\overline{t}}^{SM}$ observed and $10.8^{+6.7}_{-3.8} \times \sigma_{t\overline{t}t\overline{t}}^{SM}$ expected are calculated at the 95$\%$ confidence level.