Projections of sensitivities for tttt production at HL-LHC and HE-LHC

The CMS searches for the production of four top quarks (${\rm t\overline{t} t\overline{t}}$) are used to provide projections for the High-Luminosity LHC and High-Energy LHC. Final states with same sign leptons or three or more leptons as well as multiple b-tagged jets are used in these projections. Several different scenarios for the systematic uncertainties are considered. For proton-proton collisions at $\sqrt{s}=14~{\rm TeV}$, the existing analysis strategies are expected to become dominated by systematic uncertainties. Evidence for ${\rm t\overline{t}t\overline{t}}$ in a single analysis will become possible with around 300 fb$^{-1}$ of High-Luminosity LHC data at 14 TeV center-of-mass energy. With these datasets the uncertainty on the measured cross section will be of the order of 33 to 43$\%$, depending on the systematic uncertainty. With 3 ${\rm ab^{-1}}$ of High-Luminosity LHC data, the cross section can be constrained to 9$\%$ statistical uncertainty and 18 to 28$\%$ total uncertainty. At High-Energy LHC it would be possible to constrain the ${\rm t\overline{t}t\overline{t}}$ cross section to within 1 to 2$\%$ statistical uncertainty.