We present new results on the commissioning of the tools in ATLAS data for mapping the substructure of hadronic jets and for distinguishing the signatures of new boosted massive particles from the QCD background. Techniques to utilize jets as more than simply surrogates for individual short distance partons allow for detailed comparisons of QCD predictions for jet mass and parton shower properties, but also for recovering regions of phase space otherwise hidden by the QCD background in which highly boosted objects decay to hadrons. Two ``fat'' jet algorithms are used, along with the filtering jet grooming technique pioneered by ATLAS. Measurements of the jet invariant mass for each jet algorithm are compared to multiple Monte Carlo event generators and to NLO predictions. The substructure of these jets is directly probed by first measurements of the splitting scales within these jets. Finally, candidate boosted top quark events collected in the 2010 data are analyzed in detail for the substructure properties of hadronic "top-jets" in the final state.
Dr David W. Miller (SLAC and Stanford University)
Prof. Ariel Schwartzman (SLAC and Stanford University)