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 (${\tilde{b}}_1$ and ${\tilde{t}}_1$) 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 ${\tilde{b}}_1$ is the lightest squark and decays via ${\tilde{b}}_1\to b{\tilde{\chi }}_1^0$, where ${\tilde{\chi }}_1^0$ is the lightest neutralino. The one-lepton final state targets models where bottom or top squarks are produced and can decay into multiple channels, ${\tilde{b}}_1\to b{\tilde{\chi }}_1^0$ and ${\tilde{b}}_1\to t{\tilde{\chi }}_1^{\pm }$, or ${\tilde{t}}_1\to t{\tilde{\chi }}_1^0$ and ${\tilde{t}}_1\to b{\tilde{\chi }}_1^{\pm }$, where ${\tilde{\chi }}_1^{\pm }$ is the lightest chargino and the mass difference $m_{{\tilde{\chi }}_1^{\pm }}-m_{{\tilde{\chi }}_1^0}$ 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.

50 pages in total, author list starting page 34, 7 figures, 10 tables, submitted to JHEP, All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/SUSY-2016-28/

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