Search for stop pair production in di-tau final states (full Run 2)

A search for pair production of the supersymmetric partner of the top quark, the top squark, in proton-proton collision events at $ \sqrt{s} = 13$ TeV is presented in final states containing at least one hadronically decaying tau lepton and large missing transverse momentum. This final state is highly sensitive to high-$\tan\beta$ or higgsino-like scenarios in which decays of electroweakinos to tau leptons are dominant. The search uses a data sample corresponding to an integrated luminosity of 138 $\text{fb}^{-1}$, which was recorded with the CMS detector during 2016--2018. No significant excess is observed with respect to the standard model backgrounds. Exclusion limits at 95\% confidence level on top squark and lightest neutralino masses are presented under the assumptions of simplified models. The search excludes top squark masses up to 1150 GeV for a nearly massless neutralino.