Expected performances of jet, $\tau$ and $E_{t}$ reconstruction in ATLAS

The accurate knowledge of the ATLAS detector response in the measurement of jets, $\Etmiss$ and hadonic $\tau$ decays is very important in many interesting physics channels (precise top quark mass measurement, SUSY, SM and MSSM Higgs). The ATLAS jet/Etmiss group is performing a detaliled study of the expected performances of the detector. Although the results reported in this paper are preliminary, they indicate that the physics performance predicted at the time of the Technical Design Report may be achieved by the final detector.