First Measurements of Jet Substructure in ATLAS

The latest findings on the study and use of jets with substructure is discussed. A comparison of jet mass and splitting scale in data and Monte Carlo is provided, for anti-k_T R = 1.0 jets and Cambridge-Aachen R = 1.2 jets, the latter with splitting and filtering applied. Systematic uncertainties and the effect of pile-up are included. Finally the application of jet substructure to Higgs searches and boosted top identification is presented and the first results of Cambridge-Aachen R = 1.2 jet mass in 2011 data are shown (if approved). This poster is aiming for presentation at EPS.