After a short review of the Standard Model of Elementary Particle Physics and its minimal supersymmetric extension, the MSSM, a global analysis of two highly simplified supersymmetric models, the CMSSM and the NUHM1 is presented, with a focus on the fine-tuning of these models. A new, phenomenologically motivated measure for fine-tuning is introduced. In addition, a search for supersymmetry in final states with four leptons is presented, where a procedure for the consideration of trigger efficiencies with a focus on the calculation of uncertainties on the sum of event weights is given. Finally, limits are set in two simplified models for the direct, associate production of two neutralinos.
Keywords: High Energy Physics; Particle Physics; BSM Physics; Supersymmetry; Triggers; Global Fits; Large Hadron Collider; ATLAS
