Development of a new reconstruction and classification method for Tau leptons and its application in the ATLAS detector at the LHC

Abstract

This thesis presents a new method for the reconstruction and classification of hadronically decaying tau leptons in the ATLAS detecor at the LHC. It also presents a possible application of the new methods.<br /> The new reconstruction method follows the <em>energy flow</em> approach, which aims at reconstructing every single particle in a collision, and applies it to hadronically decaying tau leptons.<br /> This provides access to the tau decay mode and also improves the energy and spatial resolution of the tau.<br /> The new classification method makes use of so-called kinematic tau variables, which capture the kinematics of the tau decay. By combining several of these variables, it is possible to further improve the decay mode classification of the tau leptons. By taking into account the decay mode, the new classification method is also capable of improving the spatial and energy resolution of reconstructed tau leptons.<br /> In a simulation-based study, it is shown that the new reconstruction and classification methods are also capable of measuring the mean tau polarisation in the decays of a Z-Boson into two taus.