Search for direct top squark pair production in the all-hadronic final state in proton-proton collisions at sqrt(s) = 13 TeV

A comprehensive search for direct production of top squark pairs in events with jets and large transverse momentum imbalance is presented. The data were collected in proton-proton collisions at a center-of-mass energy of $13~\mathrm{TeV}$ and correspond to an integrated luminosity of $35.9~\mathrm{fb}^{-1}$. The search targets a variety of signal models of direct top squark production, including models for which the top squark and neutralino masses are nearly degenerate. Dedicated object reconstruction tools are developed to exploit the unique characteristics of the signal topology. No significant excess of events above the standard model expectation is observed. Exclusion limits are set in the context of simplified supersymmetric models of top squark pair production and various decay hypotheses. Top squark and neutralino masses up to $1040~\mathrm{GeV}$ and $610~\mathrm{GeV}$, respectively, are probed under the model assumptions.