b-Jet Identifikation in Jet-Substruktur mit dem CMS Experiment am LHC

Finn Feindt
Sep 2013

Thesis Type:

There are a large number of extensions to the Standard Modell of particle physics, which try to solve open questions in particle and astrophysics. In many cases new, heavy particles, which have not yet been discovered, occur in such models. Considering the growing centre of mass energies and event rates, achieved in modern particle accelerators, the probability to create and detect such particles in significant numbers increases. Due to its high mass the top quark is expected to be a favoured decay product of such undiscovered particles and to be produced with high momentum because of the Lorentz boost. This contains certain experimental difficulties, because the decay prdoducts of hadronically decaying top quarks are collimated to top jets, if they occur with high momentum. These top jets have substructure, which can be analysed by certain algorithms. The subject of this thesis is to examine, in how far algorithms for the identification of b-jets, could be used within the substructure of top jets. The top jets are selected with the CMS-Top-Tagging algorithm. It is shown that the use of this method, on data and simulation, leads to satisfying agreements. A comparable analysis that uses the HEP-Top-Tagging algorithm is used as reference. Apart of that, an analysis on the b-tagging efficiencies in this environment is done.