A search for production of the supersymmetric partners of the top quark, top squarks, is presented.The search is based on proton-proton collision events containing multiple jets, no leptons, and large transverse momentum imbalance.The data were collected with the CMS detector at the CERN LHC at a center-of-mass energy of 13 TeV, and correspond to an integrated luminosity of 137 $fb^-1$.The targeted signal production scenarios are direct and gluino-mediated top squark production, including scenarios in which the top squark and neutralino masses are nearly degenerate.The search utilizes novel algorithms based on deep neural networks that identify hadronically decaying top quarks and W bosons, which are expected in many of the targeted signal models.No statistically significant excess of events is observed relative to the expectation from the standard model, andlimits on the top squark production cross section are obtained in the context of simplified supersymmetric models for various production and decay modes.Exclusion limits as high as 1310 GeV are established at the 95% confidence level on the mass of the top squark for direct top squark production models,and as high as 2260 GeV on the mass of the gluino for gluino-mediated top squark production models.These results represent a significant improvement over the results of previous searches for supersymmetry by CMS in the same final state.

The expected 95% CL upper limit on the production cross section of the T5ttcc simplified model as a function of the gluino and LSP masses. The uppser limits do not take into account contributions from direct top squark pair production; however, its effect is small for $m_{\tilde{\chi}^0_1} > 600 GeV$, which corresponds to the phase space beyond the exclusions based on direct top squark pair production. The excluded regions based on direct top squark pair production from this search and earlier searches are indicated by the hatched areas.