Search for Supersymmetry in Events with a Muon and Jets at the CMS detector

Supersymmetry is a promising addition to the Standard Model of elementary particle physics, offering a solution to the hierarchy problem and presenting a dark matter candidate. It assigns a boson to every Standard Model fermion and vice versa, approximately doubling the number of particles. So far no evidence could be given for a supersymmetric world. Experiments at the LEP and Tevatron accelerators have set limits on the parameters of SUSY models, constraining mass range of the postulated particles. This thesis takes up the search for supersymmetry using 36 pb−1 of data collected at the CMS detector in 2010. Assuming R-parity conservation and working within the framework of mSUGRA, the analysis is performed in the channel with one muon, several jets and substantial missing energy. Supersymmetric decays are characterized by long cascades ending with the stable lightest supersymmetric particle which escapes the detector unseen. The signal’s topology is mimicked by processes of the Standard Model. Cuts are applied to reduce these backgrounds while keeping the signal efficiency high. To gain a better understanding of the QCD multi-jet background a method is introduced to extract it directly from the data. Moreover, systematic uncertainties on the signal and background estimates are evaluated. Finding the data to be in accordance with the Standard Model prediction, exclusion limits are set within the supersymmetric model of minimal supergravity. The limits from previous experiments can be confirmed.