Model Unspecific Search for New Physics with High pT Photons in CMS

In 2009 the LHC collider at the European center of particle physics CERN will start operations, colliding protons with a center of mass energy of up to 14 TeV. Designed as a large multi purpose detector CMS 3 will then start taking collision data. CMS will perform precision measurements within the Standard Model of particle physics and expand the search for new physical phenomena into regions that have not yet been probed by previous experiments. Many theories about what physics beyond the Standard Model at the TeV scale might look like have been proposed. Together these models leave room for a broad spectrum of possible experimental signatures that one might look for in the data. Various analyses focus on processing the available information with the aim of finding evidence for a specific model of choice. MUSiC as a Model Unspecific Search in CMS provides a complementary approach by scanning the data for noteworthy deviations from the Standard Model expectation while making only basic assumptions about the nature of new physics. This is achieved by employing dedicated algorithms which evaluate several distributions within a number of specified event classes. Taking into account both statistical and systematic uncertainties potential deviations are analyzed and quantified in terms of significance. A more detailed description of the necessary analysis steps is presented in this work. Aspects of event reconstruction and the processing of the data are outlined with a special focus on photon selection. The search algorithms, which estimate significances by the application of p-values, are explained and the treatment of systematic uncertainties is discussed. Statistical aspects of the search algorithms are evaluated emphasizing the importance of coverage properties of the employed p-values. Test scenarios with high energetic photons as a potential signature of new physics are presented in order to demonstrate the functionality and operational reliability of the chosen approach.