Search for top squark pair production in the dilepton final state using 137/fb of proton-proton collision integrated luminosity at sqrt(s) = 13 TeV

A search for supersymmetric partners of the top quark is presented in final states with two oppositely charged leptons (electrons or muons), jets identified as originating from b quarks, and missing transverse momentum. The search uses data from proton-proton collisions at $\sqrt{s}=13~\mathrm{TeV}$ collected from 2016 to 2018 using the CMS detector, amounting to $137~\mathrm{fb}^{-1}$ of integrated luminosity. Hypothetical signal events are efficiently separated from the dominant top-quark pair background with requirements on the significance of missing transverse momentum and transverse mass variables. No significant deviation is observed from the expected background. Exclusion limits are set in the context of simplified supersymmetric models with pair-produced top squarks. For top squarks decaying exclusively to a top quark and a neutralino, exclusion limits are placed at $95\%$ confidence level on the mass of the lightest top squark up to $925~\mathrm{GeV}$ and on the lightest neutralino up to $450~\mathrm{GeV}$. If the decay proceeds via an intermediate chargino, the exclusion limit at $95\%$ confidence level of the lightest top squark reaches up to $850~\mathrm{GeV}$ for neutralino masses below $420~\mathrm{GeV}$. For top squarks undergoing a cascade decay through charginos and sleptons, the mass limits reach up to $1.4~\mathrm{TeV}$ for the top squark and up to $900~\mathrm{GeV}$ for the lightest neutralino.