Searches for the Supersymmetric Partner of the Top Quark, Dark Matter and Dark Energy at the ATLAS Experiment

Description

Astrophysical observations implying the existence of Dark Matter and Dark Energy, which are not described by the Standard Model (SM) of particle physics, have led to extensions of the SM predicting new particles that could be directly produced at the Large Hadron Collider (LHC) at CERN. Based on 2015 and 2016 ATLAS proton-proton collision data, this thesis presents searches for the supersymmetric partner of the top quark, for Dark Matter, and for DarkEnergy, in signatures with jets and missing transverse energy. Muon detection is key to some of the most important LHC physics results, including the discovery of the Higgs boson and the measurement of its properties. The efficiency with which muons can be detected with the ATLAS detector is measured using Z boson decays. The performance of high-precision Monitored Drift Tube muon chambers under background rates similar to the ones expected for the High Luminosity-LHC is studied. Front Matter ....Pages i-xiii Introduction (Nicolas Maximilian Köhler)....Pages 1-2 Front Matter ....Pages 3-3 The Standard Model of Particle Physics (Nicolas Maximilian Köhler)....Pages 5-16 Dark Matter and Dark Energy (Nicolas Maximilian Köhler)....Pages 17-25 Supersymmetry (Nicolas Maximilian Köhler)....Pages 27-33 Front Matter ....Pages 35-35 The Large Hadron Collider at CERN (Nicolas Maximilian Köhler)....Pages 37-44 The ATLAS Detector (Nicolas Maximilian Köhler)....Pages 45-57 Front Matter ....Pages 59-59 Muon Reconstruction and Identification (Nicolas Maximilian Köhler)....Pages 61-66 Muon Efficiency Measurement (Nicolas Maximilian Köhler)....Pages 67-79 Performance of Monitored Drift Tube Muon Chambers at High Rates (Nicolas Maximilian Köhler)....Pages 81-90 Front Matter ....Pages 91-91 Searches for New Particles (Nicolas Maximilian Köhler)....Pages 93-102 The Search for the Light Top Squark (Nicolas Maximilian Köhler)....Pages 103-160 The Search for Dark Matter (Nicolas Maximilian Köhler)....Pages 161-179 The Search for Dark Energy (Nicolas Maximilian Köhler)....Pages 181-189 Sensitivity Studies Exploiting Multivariate Techniques (Nicolas Maximilian Köhler)....Pages 191-206 Summary (Nicolas Maximilian Köhler)....Pages 207-208 Back Matter ....Pages 209-263