Search for supersymmetry in events with b-tagged jets and missing transverse momentum in pp collisions at $\sqrt{s}=13$ 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 ${\overline{b}}_{1}\to t{\overline{\chi }}_{1}^{±}$ , or ${\overline{t}}_{1}\to t{\overline{\chi }}_{1}^{0}$ and ${\overline{t}}_{1}\to b{\overline{\chi }}_{1}^{±}$ , where ${\overline{\chi }}_{1}^{±}$ is the lightest chargino and the mass difference ${m}_{{\overline{\chi }}_{1}^{±}}-{m}_{{\overline{\chi }}_{1}^{0}}$ 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.