Search for Supersymmetry with b-jets and 1 lepton

A search for supersymmetric particles in events with large missing transverse momentum, heavy flavour jet candidates and one lepton ($e$,$\mu$) in $\sqrt{s} = 7$ TeV proton-proton collisions is presented. In a data sample corresponding to an integrated luminosity of 1.035 fb$^{-1}$ recorded by the ATLAS experiment at the Large Hadron Collider, no significant excess is observed with respect to the prediction for Standard Model processes. For $R$-parity conserving models in which stops are the only squarks to appear in the gluino decay cascade, gluino masses below 500-520 GeV -- depending on the stop mass -- are excluded at the 95% C.L. in case of on-shell $\tilde{g}\rightarrow t\tilde{t}_1$ decays and assuming $\tilde{t}_1 \rightarrow b \tilde{\chi}^{\pm}$. Results are also interpreted in the context of simplified models assuming off-shell $\tilde{g} \rightarrow \tilde{t}_1 t$ decays and $\tilde{t_1} \rightarrow t \tilde{\chi^1_0} $: gluino masses below 570 (540) GeV are excluded at the 95% C.L. for $m_{\tilde{\chi^0_1}}$ below 40 (80) GeV.