Measurement of the B-Tagging Efficiency in the CMS Experiment with the First LHC Collisions

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Jafari, Abideh | 2011

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Type of Document: Ph.D. Dissertation
Language: English
Document No: 42544 (04)
University: Sharif University of Technology
Department: Physics
Advisor(s): Ardalan, Farhad
Abstract:
Jets originating from bottom (b) quarks, play an important role in the study of Standard Model processes together with the search for new physics. In the CMS experiment a considerable e?ort is dedicated to the development and the performance study of so-called b-tagging algorithms. On the other hand, the top quark which is produced in pair (tt¯) with a high rate at the LHC, decays near 99% of the time to a b-quark. Hence it provides a rich source of b-quark jets, suitable for b-jet identi?cation studies. In this thesis, a fully data-driven method to measure the b-tagging e?ciency, using top quark events in its semi-electron ?nal state, is developed. The results of the application of the method on the ?rst LHC collisions in 2010 is reported. The method can be extended to a simultaneous top quark cross section and b-tagging e?ciency measurement, therefore resulting in smaller undertainties
Keywords:
Standard Model ; Top Quark ; Compact Muon Solenoid (CMS)Test ; Center European de Recherche Nuclear (CERN) ; Electron ; Hadronic Jet ; Large Hadronic Collider ; Efficiency ; B-Quark