Search for the SM Higgs boson in the H tau(lep)tau(had) decay channel

In July 2012 a milestone in the field of particle physics was reached: the discovery of the long awaited Higgs boson. Although the Higgs boson had been theoretically predicted over 50 years ago, it took time and the largest machine ever built - the Large Hadron Collider (LHC) - to confirm its existence. The production of the Higgs boson underlies the laws of statistics: Since the Higgs boson is not stable, only its decay products can be detected with the detectors located at the colliding points of the LHC. It is then the physicists task to separate those events which presumably included a Higgs boson from those without. To do this, properties of the decay products (such as angular distribution, total mass, etc.) are measured and compared to the theoretically expected distributions. From the difference between the theoretically expected and measured distributions, conclusions towards the existence and properties of the Higgs boson can be drawn. This book gives an overview of the theory describing the Higgs boson, the results presented in July 2012 as well as the reconstruction of particles with the ATLAS detector. It focuses on the decay of the Higgs boson into two tau leptons, from which one decays into leptons and one into hadrons, and how the sensitivity towards a SM Higgs boson can be increased by focusing on the decay products of the hadronically decaying tau lepton.