Search for a scalar partner of the top quark in the jets plus missing transverse momentum final state at √s = 13 TeV with the ATLAS detector

Abstract

A search for pair production of a scalar partner of the top quark in events with four or more jets plus missing transverse momentum is presented. An analysis of 36.1 fb−1 of √s = 13 TeV proton–proton collisions collected using the ATLAS detector at the LHC yields no significant excess over the expected Standard Model background. To interpret the results a simplified supersymmetric model is used where the top squark is assumed to decay via t ̃ → t(∗)χ ̃0 and t ̃ → bχ ̃± → bW(∗)χ ̃0, where χ ̃0 (χ ̃±) denotes the lightest neutralino 1111111 (chargino). Exclusion limits are placed in terms of the top-squark and neutralino masses. Assuming a branching ratio of 100% to tχ ̃01, top-squark masses in the range 450−1000 GeV are excluded for χ ̃ 01 masses below 160 GeV. In the case where mt ̃1 ∼ mt + mχ ̃ 01 , top-squark masses in the range 235−590 GeV are excluded.