Projection of the top quark spin correlation measurement and search for top squark pair production at the HL-LHC

The CMS prospects for the high-luminosity phase of the LHC on the measurement of the top quark spin correlation is presented, using events containing two oppositely charged lepton pairs (e$\mu$) produced in proton-proton collisions at a center-of-mass energy of 14 TeV assuming an integrated luminosity of $3~\mathrm{ab}^{-1}$. We investigate the normalised strength of the spin correlation in the sample and hence, provide a first performance study in future spin correlation measurements at 14 TeV. As an application, these observables are used in a Deep Neural Network to search for pair production of supersymmetric (anti-)top scalar quarks decaying into (anti-)top quarks and neutralinos, which escape the detector undetected. The observables sensitive to top quark spin correlation allow to study the corridor where the mass difference between the top scalar quark and the neutralino is about equal to the top quark mass. Compared to existing Run 2 results, this work will particularly push the discovery potential to the most natural top squark mass values below 300 GeV by one order of magnitude.