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Early discoveries at the LHC with the CMS silicon strip tracker

Final Activity Report Summary - LHC-PHYS (Early discoveries at the LHC with the CMS silicon strip tracker)

This project was related to the largest and most powerful particle accelerator ever built, the Large Hadron Collider (LHC) at CERN. In this 27-kilometre ring-shaped accelerator, protons of an energy of 7 TeV will be collided head-on in four different locations, where dedicated experiments have been built. The project concerned one of these experiments, the Compact Muon Solenoid (CMS) experiment. The original goal of this project was related to detector operation and analysis of the first data collected by CMS. However, due to repeated delays no real LHC data could be analysed. Thus, the focus has been on the preparation for the analysis of the first LHC data, in particular the detection of particles called quarkonia, decaying with a large branching fraction into two muons, which can be detected precisely in CMS.

On the one hand, some characteristics of these particles, like their mass, are already accurately known from previous experiments, and hence they are extremely useful for issues like detector calibration and alignment. On the other hand, the underlying physics production mechanism is still not well understood. During the project, different studies were performed on how to shed light on their production mechanism. It resulted in presentations in international conferences and publications. In addition, still using quarkonia, studies were performed on how to extract the muon efficiency at low transverse momenta.