Supersymmetry: A study of the supersymmetric opposite sign di-lepton channel

The LHC accelerator (Large Hadron Collider) at CERN (Organisation européenne pour la recherce nucléaire) at the border of Switzerland and France is about to start up, and with it a new ear in particle physics. Physicists involved with the ATLAS detector (A Toiroidal Lhc ApparatuS) hope to find answers to several unsolved problems with todays model of particle physics: the Standard Model. A partial solution could be an extended version of the Standard Model: Supersymmetry, which will more than double the number of particles in nature. If supersymmetry should prove to exist, we need efficient ways to recognize a supersymmetric manifestation in the detector. This study looks at signatures of a specific version of supersymmetry: the minimal supergravity model (mSUGRA), and a decay-chain that leads to at least two leptons (electrons or muons) of opposite charge, quark-jets and missing transverse energy from the end-product of the decay-chain: a weakly interacting stable supersymmetric particle. The study involves lepton identification and lepton identification efficiencies, event-selection requirements and finally the discovery potential at the ATLAS detector. Because mSUGRA has several free parameters, 6 different points in parameter-space were investigated. It is shown that the prospects for discovery are good for several of the chosen mSUGRA points.