Measurement of jet shapes in top pair events using the ATLAS detector.

A measurement of jet shapes in top pair events using 1.8 /fb of $\sqrt{s} = 7$ TeV pp collision data recorded by the ATLAS detector at the LHC is presented. Samples of top pair events are selected in both the single-lepton and dilepton final states. The differential and integrated shapes of the jets initiated by bottom-quarks from the top-quark decays are compared with those of the jets originated by light-quarks from the hadronic W -boson decays in the single-lepton channel. Light-quark jets are found to have a narrower distribution of the momentum flow inside the jet cone than b-quark jets.