UC Berkeley

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 s=13$$ \sqrt{s}=13 $$ TeV collected by the ATLAS experiment at the Large Hadron Collider. Direct production of pairs of bottom and top squarks (b¯1$$ {\overline{b}}_1 $$ and t¯1$$ {\overline{t}}_1 $$) 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 b¯1$$ {\overline{b}}_1 $$ is the lightest squark and decays via b¯1→bχ¯10$$ {\overline{b}}_1\to b{\overline{\chi}}_1^0 $$, where χ¯10$$ {\overline{\chi}}_1^0 $$ is the lightest neutralino. The one-lepton final state targets models where bottom or top squarks are produced and can decay into multiple channels, b¯1→bχ¯10$$ {\overline{b}}_1\to b{\overline{\chi}}_1^0 $$ and b¯1→tχ¯1±$$ {\overline{b}}_1\to t{\overline{\chi}}_1^{\pm } $$, or t¯1→tχ¯10$$ {\overline{t}}_1\to t{\overline{\chi}}_1^0 $$ and t¯1→bχ¯1±$$ {\overline{t}}_1\to b{\overline{\chi}}_1^{\pm } $$, where χ¯1±$$ {\overline{\chi}}_1^{\pm } $$ is the lightest chargino and the mass difference mχ¯1±−mχ¯10$$ {m}_{{\overline{\chi}}_1^{\pm }}-{m}_{{\overline{\chi}}_1^0} $$ 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.