Measurement of the Top Quark Mass in Dileptonic Top Quark Pair Decays with $\mathbf{\sqrt{s}=7}$~TeV ATLAS Data

The top quark mass in dileptonic top quark pair decays was measured using $4.7~\mathrm{fb}^{-1}$ of $\sqrt{s}=7~\mathrm{TeV}$ proton-proton ($pp$) collision data recorded by the ATLAS experiment at the LHC in 2011. The event topology is characterised by the presence of two charged leptons, at least two neutrinos and several jets, two of which originate from bottom quarks. Using the template method and the m$_{\ell b}$ observable, defined as the average invariant mass of the two charged lepton plus $b$-jet pairs in each event, the top quark mass is measured to be $173.09 \pm 0.64~(\mathrm{stat}) \pm 1.50~(\mathrm{syst})~\mathrm{GeV}$. This proceeding is based on a preliminary result, which has been superseded meanwhile.