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

Abstract

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.