Scalar Top Quark Search with Jets and Missing Momentum in pp Collisions at 7 TeV

The results of CMS searches for Supersymmetry are interpreted in the context of Simplified Models. A limited set of hypothetical particles and decay chains are introduced to produce a given topological signature. The amplitudes describing the production and decays of these particles are parametrized in terms of the particle masses and their branching ratios to daughter particles. Among the new possible particles, the Higgs mechanism of electroweak symmetry breaking gives a special role to the partner of the third generation SM particles. In this thesis, I will describe how the comparison of different search strategies on multiple simplified models helps to quantify that the LHC has not put any stringent bounds on them yet. The 4.98 fb-1 of data collected by CMS, was analyzed to search for the scalar stop in the jets plus met final state. In particular, I will focus on the ttbar background; I will describe in detail the handles used to reduce it and the technique adopted to predict this contribution from data. The data is found to be in agreement with the predicted backgrounds. An upper limit on the cross section times branching ratio is set for the decays stop to LSP plus top and stop to LSP plus b W through a chargino final state.