Search for Dark Matter with ATLAS

This thesis describes in detail a search for weakly interacting massive particles as possible dark matter candidates, making use of so-called mono-jet events. It includes a detailed description of the run-1 system, important operational challenges, and the upgrade for run-2. The nature of dark matter, which accounts for roughly 25% of the energy-matter content of the universe, is one of the biggest open questions in fundamental science. The analysis is based on the full set of proton-proton collisions collected by the ATLAS experiment at the Large Hadron Collider at vs = 8 TeV. Special attention is given to the experimental challenges and analysis techniques, as well as the overall scientific context beyond particle physics. The results complement those of non-collider experiments and yield some of the strongest exclusion bounds on parameters of dark matter models by the end of the Large Hadron Collider run-1. Details of the upgrade of the ATLAS Central Trigger for run-2 are also included.

Auteur
The author obtained her Diploma in Physics at the University of Mainz (JGU), Germany, in 2011 upon completion of her research project on a differential cross-section measurement of Z-boson production with the ATLAS experiment. As a CERN doctoral student, funded by a Wolfgang-Gentner-Scholarship, she made essential contributions to the operation and upgrade of the ATLAS Central Trigger and conducted a search for Dark Matter in so-called mono-jet events. She obtained her PhD "with distinction" at JGU in May 2015 and was awarded prizes for an outstanding thesis both from the ATLAS collaboration and from the physics department of JGU. Since March 2015 she has been a postdoctoral researcher at Stockholm University, coordinating the ATLAS search for leptoquarks.

Contenu
Introduction.- Theory and Motivation.- The Standard Model of Particle Physics.- Dark Matter.- Proton-Proton Collisions.- Mono-Jet Events as Dark Matter Signature at Colliders.- Large Hadron Collider.- The ATLAS Experiment.- Operation of the Central Trigger during run-I.- Upgrade of the Central Trigger.- Analysis Strategy.- Data and Simulated Samples.- Physics Objects Denitions.- Event Selection.- Background Estimation.- Results and Interpretation.- Prospects with Future LHC DataConclusion.