Improving the $t\bar t+$jets background rejection in a search for supersymmetric particles in events with leptons and multiple jets at the ATLAS experiment

In this report, an attempt to select $b$-quark pairs from $g\rightarrow b\bar b$ in the $t\bar t+$jets background simulation of a search for supersymmetric particles in events with leptons and multiple jets is presented. $b$-tagged jets are paired and selected exploiting kinematic differences between these from gluon-splitting and mainly those from top quark decays. It is found that $(33\pm3)\%$ of the built pairs from the background in the signal region consist of two $b$-tagged jets from gluon-splitting. No large improvement of the signal-to-background ratio can be achieved from this. The fraction of built $b$-tagged jet pairs that originate from a gluon can be increased to above $60\%$ with a cut on a discriminating variable.