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

The top quark mass in dileptonic top quark pair decays is measured using $4.7~\mathrm{fb}^{-1}$ of proton-proton collision data recorded at the centre of mass energy $\sqrt{s}=7~\mathrm{TeV}$ 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 lepton plus $b$-jet pairs in each event, the top quark mass is measured to be $173.09 \pm 0.64_\mathrm{stat} \pm 1.50_\mathrm{syst}~\mathrm{GeV}$.