Constraining the 19D phenomenological Minimal Supersymmetric Standard Model with the ATLAS Experiment

The Standard Model of elementary particles is a highly successful theory, but it has limitations, as it cannot explain gravity, dark matter, and other phenomena. Supersymmetry (SUSY) is a Beyond Standard Model theory addressing some gaps. For example, if R-parity is conserved, the lightest supersymmetric particle is a good candidate for dark matter. Many searches for SUSY particles have been conducted at the ATLAS and CMS experiments at the Large Hadron Collider. So far, no significant deviations from the Standard Model have been observed, but these studies have set strict limits on the existence of supersymmetric particles. In this thesis, multiple ATLAS Run-2 SUSY searches are reinterpreted within the framework of the 19-dimensional phenomenological Minimal Supersymmetric Standard Model (pMSSM). Both strong and electroweak SUSY processes are analyzed under the assumption of R-parity conservation. This study also considers limits from other experiments, such as dark matter searches, to complement ATLAS results. This work comprehensively assesses ATLAS's sensitivity to SUSY.