Supervisor's Foreword; Acknowledgments; Contents; 1 Introduction; References; 2 The Standard Model and Its Supersymmetric Extension; 2.1 The Lagrangian of the Standard Model; 2.2 Electroweak Symmetry Breaking; 2.3 Renormalizations in the Standard Model; 2.4 Observed Particles; 2.5 Unanswered Questions in the Standard Model; 2.6 Supersymmetry; 2.7 Supersymmetry Breaking; 2.8 The Minimal Supersymmetric Standard Model; 2.9 Soft Supersymmetry-Breaking Parameters; 2.10 Gauge-Mediated Supersymmetry Breaking; 2.11 The Phenomenology of the MSSM; 2.12 The Status of Searches for Supersymmetry

2.12.1 General Status2.12.2 GMSB Searches; References; 3 The LHC and the CMS Experiment; 3.1 The Large Hadron Collider; 3.2 The CMS Detector; 3.2.1 Inner Trackers; 3.2.1.1 Pixel Tracker; 3.2.1.2 Strip Tracker; 3.2.2 Electromagnetic Calorimeter and Preshower Detector; 3.2.3 Hadronic Calorimeter and Forward Detectors; 3.2.4 Muon Trackers; 3.2.4.1 Drift Tubes; 3.2.4.2 Cathode Strip Chambers; 3.2.4.3 Resistive Plate Chambers; 3.3 Trigger System; 3.4 Object Reconstruction; 3.4.1 Tracks; 3.4.2 Photons; 3.4.3 Electrons; 3.4.4 Muons; 3.4.5 Jets; 3.4.6 Particle Flow and Missing Transverse Energy

3.5 Physics Simulation3.5.1 Monte-Carlo Event Generators; 3.5.2 CMS Detector Simulation; References; 4 Data Collection and Event Selection; 4.1 Overview of Data Samples; 4.2 Triggers; 4.3 Photon Selection; 4.4 Electron Selection; 4.5 Muon Selection; 4.6 Full Selection Criteria; 4.7 Jet Selection; 4.8 Simulation; 4.8.1 Simulation Data Sets; 4.8.2 Pileup Reweighting; 4.8.3 Efficiency Corrections; References; 5 Data Analysis; 5.1 Outline; 5.2 Fake Photon Background Due to Electrons; 5.2.1 Electron Proxy Sample Definition (e-gamma); 5.2.2 Transfer Factor Measurement (e-gamma)

5.2.3 Individual Fake Rate Measurement (e-gamma)5.2.4 Systematic Uncertainties on Tag-and-Probe (e-gamma); 5.2.5 Fake Rate Function Determination (e-gamma); 5.2.6 Systematic Uncertainty on the Fake Rate Function (e-gamma); 5.2.7 Dependence of the Fake Rate on Track Multiplicity; 5.2.8 mu-gamma Channel; 5.2.9 Validity Evaluation; 5.3 Fake Photon Background Due to Jets; 5.3.1 Overview; 5.3.2 The Hadron Fraction (mu-gamma); 5.3.3 Proxy Sample and Transfer Factor (mu-gamma); 5.3.4 e-gamma Channel; 5.3.5 Closure Test; 5.4 Background Due to Lepton Mis-identification; 5.4.1 Overview

5.4.2 Fake Electron Proxies5.4.3 Fake Muon Proxies; 5.5 EWK Background; 5.5.1 The Standard Model V-gamma Cross Section; 5.5.2 Normalization of the V-gamma and Fake Lepton Samples; 5.5.3 Multiboson and tt-gamma Backgrounds; 5.6 Estimations of the Efficiency Scale Factors; 5.6.1 Factorization of the Full Selection Efficiency; 5.6.2 Offline Selection Efficiency; 5.6.2.1 Lepton Selection ESF; 5.6.2.2 Photon Selection ESF; 5.6.3 Trigger Efficiency; References; 6 Results and Interpretations; 6.1 Results; 6.2 Signal Expectations; 6.3 Systematic Uncertainties