Tagging of hadronically decaying massive particles in ATLAS

The ability to differentiate between hadronically decaying massive particles and other sources of jets is increasingly important to the LHC physics program. A variety of algorithms which are used in ATLAS to identify large-R jets from such decays are presented, including both cut-based taggers and machine learning discriminants. In order to understand the validity of these identification algorithms, expectations are compared with data in well-understood final states, allowing for the derivation of scale factors accounting for differences between simulation and data.