Measurement of the 3 Top Quark Production

A search for the standard model production of three top quarks is presented. The data analyzed were collected with the CMS detector at the CERN LHC in proton-proton collisions at a center-of-mass energy of $13~\mathrm{TeV}$ and correspond to an integrated luminosity of $138~\mathrm{fb}^{-1}$. Selected events are required to contain jets and either one lepton (electron or muon), two same-sign charged leptons, or at least three leptons. The results are derived from the combination of these three lepton categories. Novel multivariate techniques are employed to take full advantage of kinematic differences between the studied signal and the major background. This analysis provides the first LHC result specifically targeting three-top-quark production. No significant deviations with respect to the standard model predictions are observed, and an upper limit of $25~\mathrm{fb}$ is set on the signal cross section at $95\%$ confidence level.