Search for Supersymmetry in Like Sign Dilepton Events in 2010 GMS Data

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Bakhshiansohi, Hamed | 2011

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Type of Document: Ph.D. Dissertation
Language: English
Document No: 42224 (04)
University: Sharif University of Technology
Department: Physics
Advisor(s): Ardalan, Farhad; Pape, Luc
Abstract:
We search for supersymmetry in the same-sign dilepton final state in the first 35 pb1 of data collected by the CMS detector and find no evidence of new physics at this point. Since true same-sign physics backgrounds, such asWWjj, are negligible for this amount of integrated luminosity, we focus our attention on data-driven estimations of the backgrounds where one (W+jets and tt backgrounds) or both of the leptons (QCD background) are fake. We use the generalized fake ratio method documented to estimate the rates for these fake backgrounds. Another source of backgrounds in the case of electrons is the charge-flip, where the charge of one of the electrons in an opposite-sign di-electron pair is wrongly measured. We estimate this background by determining a charge-flip probability from Z-boson events.
Keywords:
Supersymmetry ; Large Hadronic Collider ; Compact Muon Solenoid (CMS)Test ; Center European de Recherche Nuclear (CERN) ; Sam-Sign Dilepton