Search for Supersymmetry in pp Collisions at $\sqrt{s}$ = 8 TeV with a Photon, Lepton, and Missing Transverse Energy

This thesis presents a search for anomalous production of events with at least one photon, one electron or muon, and large missing transverse energy in proton-proton collisions at a center-of-mass energy of 8TeV. A data set corresponding to an integrated luminosity of 19.7/fb recorded in 2012 by the Compact Muon Solenoid detector at the CERN Large Hadron Collider is analyzed. The search is motivated by a class of supersymmetric extensions of the standard model with gauge-mediated supersymmetry breaking, which predicts decays of supersymmetric particles into a W boson, a photon, and highly energetic gravitinos, which are undetected and lead to a momentum imbalance in the plane transverse to the proton beams. The expected standard model background contributions of events featuring the same final state signature is estimated by separating the background processes into categories and applying estimation techniques tailored for each category. No excess of events with large missing transverse energy is observed beyond the expectations from standard model processes. The result of this search is interpreted as 95% confidence level upper limits on the production cross section of supersymmetric particles as well as generic new-physics particles in two simplified models. The cross section upper limits set by this search pose the most stringent constraint to date on the considered supersymmetric models.