Reconstruction, Energy Calibration, and Identification of Hadronically Decaying Tau Leptons

The reconstruction algorithm, energy calibration, and identification methods for hadronically decaying tau leptons in ATLAS are described in this note. The energy calibration relies on Monte Carlo samples with hadronic tau decays, and applies multiplicative factors based on the pT of the reconstructed tau lepton to the uncalibrated energy. Three identification methods are also optimized: cut-based identification, a projective likelihood, and boosted decision trees. The performance of these identification methods is shown, and systematic uncertainties on the energy scale and identification efficiencies of hadronically tau leptons are determined using Monte Carlo samples that simulate varying conditions.