Search for Bottom Squark Pair Production with the ATLAS Detector in proton-proton Collisions at $\sqrt{s}=13$ TeV

The result of a search for pair production of the supersymmetric partners of the Standard Model bottom quarks (b1) is reported. The search uses 3.2 fb$^{-1}$ of pp collisions at $\sqrt{s}=13$ TeV collected by the ATLAS experiment at the Large Hadron Collider in 2015. Bottom squarks are searched for in final state events containing large missing transverse momentum and exactly two jets identified as originating from a b-quark. No excess above the expected Standard Model background yields is observed. Exclusion limits at 95% confidence level on the mass of the bottom squark are derived in phenomenological supersymmetric R-parity-conserving models in which the $\tilde b_1$ is the lightest squark and is assumed to decay via $\tilde b_1 \rightarrow b \tilde \chi_1^0$, where $\chi_1^0$ is the lightest neutralino. Bottom squark masses up to 800(840) GeV are excluded for m($\tilde \chi_1^0$) below 360(100) GeV whilst differences in mass above 100 GeV between the $\tilde b_1$ and the $\tilde \chi_1^0$ are excluded up to m($\tilde b_1$)=500 GeV