Search for supersymmetry in events with b-tagged jets and missing transverse momentum in pp collisions at √s=13 TeV with the ATLAS detector

A search for the supersymmetric partners of the Standard Model bottom and top quarks is presented. The search uses 36.1 fb$^{−1}$ of pp collision data at $ \\sqrt{s}=13 $ TeV collected by the ATLAS experiment at the Large Hadron Collider. Direct production of pairs of bottom and top squarks ( $ {\\overline{b}}_1 $ and $ {\\overline{t}}_1 $ ) is searched for in final states with b-tagged jets and missing transverse momentum. Distinctive selections are defined with either no charged leptons (electrons or muons) in the final state, or one charged lepton. The zero-lepton selection targets models in which the $ {\\overline{b}}_1 $ is the lightest squark and decays via $ {\\overline{b}}_1\\to b{\\overline{\\chi}}_1^0 $ , where $ {\\overline{\\chi}}_1^0 $ is the lightest neutralino. The one-lepton final state targets models where bottom or top squarks are produced and can decay into multiple channels, $ {\\overline{b}}_1\\to b{\\overline{\\chi}}_1^0 $ and $ {\\overline{b}}_1\\to t{\\overline{\\chi}}_1^{\\pm } $ , or $ {\\overline{t}}_1\\to t{\\overline{\\chi}}_1^0 $ and $ {\\overline{t}}_1\\to b{\\overline{\\chi}}_1^{\\pm } $ , where $ {\\overline{\\chi}}_1^{\\pm } $ is the lightest chargino and the mass difference $ {m}_{{\\overline{\\chi}}_1^{\\pm }}-{m}_{{\\overline{\\chi}}_1^0} $ is set to 1 GeV. No excess above the expected Standard Model background is observed. Exclusion limits at 95% confidence level on the mass of third-generation squarks are derived in various supersymmetry-inspired simplified models.