Datensatz

Zusammenfassung

Supersymmetry (SUSY) provides solutions to many open problems of the Standard Model (SM) such as the hierarchy problem and the mystery of Dark Matter (DM). In some SUSY models, the supersymmetric partner of the τ-lepton, the stau ( τ̃), is predicted to be lighter than the other sleptons with a mass near the electroweak scale. Models involving co-annihilation between the stau and the lightest supersymmetric particle (LSP), which can be almost degenerate in mass, reproduce the observed relic DM density of the universe. At the LHC, staus would be pair-produced and decay into their SM counterpart and the LSP. Typical stau events would, therefore, be characterized by the presence of two SM τ-leptons and large missing energy arising from the LSP pair and the neutrinos from the tau decays. This thesis presents the search strategy for direct stau pair production with the ATLAS detector at the LHC at a center-of-mass energy of 13 TeV. The focus of the study is on final states with one hadronically and one leptonically decaying τ-lepton. The selection of signal regions is optimized to achieve the highest possible signal sensitivity using simulated data in the ATLAS detector. Stau-LSP mass regions between 170 and 270 TeV and 1 and 55 TeV, respectively, can be exluded at 95 % CL.