Tau Physics with First Data in ATLAS

Tau leptons, and particularly their hadronic decays, will play an important role at the LHC. The goals for early tau physics in ATLAS include acquiring a sample of tau leptons from data with a purity as high possible so that the identification efficiency of hadronically decaying tau leptons can be measured and the simulation can be tuned. Collecting data with an integrated luminosity of 100 pb-1 at an instantaneous luminosity of 10^31 cm-2s-1 will provide a unique opportunity to access and understand statistically significant tau samples from Standard Model processes at relatively low transverse momenta. Processes, like the production of W and Z bosons and top quark pairs with their huge cross section will lead to samples of a few hundred to a few thousand identified hadronic tau decays. Hadronically decaying tau leptons will then become a well understood probe for discovery physics like searches for Higgs bosons, SUSY, or unexpected phenomena. Feasibility studies for analyzes which can be envisaged with an integrated luminosity of 100 pb-1 are presented.