Search for direct top squark pair production in the fully hadronic final state in proton-proton collisions at sqrt(s) = 13 TeV corresponding to an integrated luminosity of 12.9/fb

A 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 TeV and correspond to an integrated luminosity of 12.9/fb. Two analyses are performed, a ``low $\Delta m$" analysis that targets scenarios with a very small difference in mass between the top squark and the neutralino, and a ``high $\Delta m$" analysis that targets topologies typical for larger mass splittings. No significant excess of events above the expected background from standard model processes is observed. Exclusion limits are set in the context of simplified models of top squark pair production under various decay hypotheses, ranging up to 860 GeV in the case of the high $\Delta m$ analysis and up to 450 GeV in the case of the low $\Delta m$ analysis.