Search for ttbar resonances at the HL-LHC and HE-LHC with the Phase-2 CMS detector

A search for a heavy resonance decaying into a ${\text{t}\overline{\text{t}}}$ pair is presented using the upgraded Phase-2 CMS detector design at the High-Luminosity LHC (HL-LHC) and High-Energy LHC (HE-LHC), with center-of-mass energies of $14$ and $27~\mathrm{TeV}$, respectively, and integrated luminosities of $3$ and $15~\text{ab}^{-1}$. Two distinct final states with either a single lepton or no leptons are considered. Jet substructure techniques and top quark identification algorithms are used for the object reconstruction. At the HL-LHC (HE-LHC), the production of a Randall--Sundrum gluon can be excluded at $95\%$ confidence level with a mass up to $6.6$ $(10.7)~\mathrm{TeV}$ or can be discovered at $5\sigma$ significance with a mass up to $5.7$ $(9.4)~\mathrm{TeV}$.