A search for supersymmetry with the ATLAS detector using kinematic shape constraints in events containing one electron or muon

Thesis

The ATLAS experiment is used to observe the √s=7 TeV proton-proton collisions produced by the LHC at CERN. This gives an unprecedented opportunity to search for physics beyond the Standard Model at hitherto unexplored kinematic regimes. Supersymmetry (SUSY) provides interesting solutions to a variety of theoretical problems that may be encountered in the Standard Model at high energy scales, while providing signatures that may be observed at the LHC. However, in order to produce a search that is sensitive to SUSY it is vital to understand how the physics that has been discovered to date may produce signatures that mimic those expected from SUSY.

Statistical models are constructed using both Monte Carlo and data-driven predictions of various background processes. The expectations are compared to the observed data for selections containing one electron or muon, each in association with jets and missing transverse momentum. Kinematic variable shapes, in the form of histograms, are used to enhance the sensitivity of the search. Squark and gluino masses in a MSUGRA SUSY model are excluded up to 1200 GeV, while gluino masses up to 900 GeV are excluded in a simplified SUSY model. Model-independent limits are also set, excluding theoretical models with efficiency times cross section above 1 fb.

Authors: Short, DR

• Publication date: 2012
• DOI: 10.5287/ora-qoj9ea8z1
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: ATLAS; experimental particle physics; supersymmetry; physics; particle physics
• Subjects: Particle physics; Physical Sciences; Physics