Search for electroweak production of supersymmetric gauginos with photons at CMS

In this thesis a search for electroweak production of gauginos in the theoretical context of gaugemediated supersymmetry is presented. Under the assumption of a bino-like mixture of the gaugeeigenstates of the lightest neutralino, being the next-to-lightest supersymmetric particle in thisanalysis, decays of the lightest neutralino into a photon and a gravitino are highly preferred. Dueto R-parity conservation, the gravitino is stable. Since it does not interact with the detector, anincreased amount of missing transverse energy is expected in the event. The search is performedusing a parked dataset corresponding to an integrated luminosity of 7.4 fb−1 , recorded by theCMS detector during the proton-proton collisions at the LHC in 2012. The search strategy isfocused on selecting high energetic photons accompanied by significantly high genuine missingtransverse energy. Due to the focus on electroweak production, the event selection favors finalstates with a moderate amount of hadronic activity, complementing the classical single photonanalysis.The analysis uses data to model the contribution of the dominant standard model backgroundprocesses by using a Monte-Carlo normalization and a fully data-driven method. The controland signal regions are defined using the ET significance and the transverse mass of the leadingphoton and the missing transverse energy, resulting in an excellent separation of background andsignal events together with good conditions for the development of the analysis in the controlregion. Sufficiently small uncertainties are achieved, ensuring sensitivity to new physics in thesignal region.Good agreement between standard model prediction and measurement is observed in the finalselection. Four statistically independent search channels are defined to perform a statistical interpretation of the results. A general gauge mediation signal scenario with electroweak productionis used to calculate upper cross-section limits at 95% confidence level. The calculated exclusionlimits indicate a significant improvement of the currently best exclusion limits in the phase spaceexamined by the analysis.