Preview

PDF, English Download (10MB) | Terms of use

Abstract

This thesis presents a novel strategy for searches for Dark Matter at particle colliders using variables that are corrected for detector effects. Dark Matter is experimentally motivated by cosmological evidence and is one of the great contemporary puzzles of physics. This thesis describes the conventional approach of searches for Dark Matter using final states with missing transverse momentum, \ptm, and hadronic jets and discusses its shortcomings. Several techniques for improvements are put forward. An analysis is presented that implements these improvements. It is performed on 3.2 fb⁻¹ of data collected by the ATLAS experiment in 2015 at √s = 13 TeV and measures an unfolded fiducial cross-section ratio in two kinematic regions and in total four differential distributions. The numerator of the ratio is defined as σ(\ptm + jets) and the denominator as σ(Z →l^+l^- + jets). The ratio leads to the cancellation of many systematic uncertainties and detector-induced effects. Limits on three Dark Matter scenarios are set using the distributions. An improved performance with respect to the conventional \ptm + jets Dark Matter search is observed. These distributions can be used to set limits on models containing new physics without using an ATLAS detector simulation. Additional studies are presented investigating further performance enhancements for a future iteration of this analysis.