Measurement of the tau lepton reconstruction and identification performance in the ATLAS experiment using $pp$ collisions at $\sqrt{s}=13~{\rm TeV}$

This document details measurements of the performance of the reconstruction and identification of hadronic tau lepton decays using the ATLAS detector. The performance of these algorithms is measured with \Zboson\ boson or top quark decays to tau leptons and uses the full 2015 dataset of $pp$ collisions collected at the LHC, corresponding to an integrated luminosity of \datalumi and a centre-of-mass energy $\sqrt{\mathrm{s}} = 13$ TeV. The measurements include the performance of the identification, trigger, energy calibration and electron discrimination algorithms for reconstructed tau candidates. The simulation to data correction factor on the offline tau identification efficiency is measured with a relative precision of 5\% (6\%) for one (three) track reconstructed tau candidates. For hadronic tau lepton decays selected by offline algorithms, the correction factor on the tau trigger identification efficiency is measured with a relative precision of 3--8\% for $p_{\rm T}({\rm \tau_{had}})<100$ GeV and 8--14\% for $100< p_{\rm T}({\rm \tau_{had}})<300$ GeV, depending on the transverse energy and the number of associated tracks. The correction factor on the tau energy scale is measured with a relative precision of 2\% (3\%) for one (three) track reconstructed tau candidates. The correction factor on the probability of misidentifying an electron as a hadronic tau lepton decay is measured with a relative precision of between 3--14\%, depending on the pseudorapidity of the reconstructed tau candidate.