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Study of systematic effects from the level of Final State Radiation in tt-background to SUSY dilepton channels
KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
2011 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Uncertainties in radiative effects of the quarks in -background in the form of final state radiation (FSR) are significant when it comes to reducing all forms of systematics that can arise from measuring the jets energy. Analysis on FSR is in general conducted on different simulated samples where one has included the radiative effect using algorithms such as PYTHIA[29]. The hypothesis is that through the re-weighting of the -background nominal sample one could add a better representation of the FSR effect. Finding a simple way to include a better description of FSR would not only save time in the simulation process but it would also be a way to reduce the systematic errors originating from limited MC statistics. Due to statistical effects coming from the simulations one cannot use the basic approach to define the effect of FSR as simply the difference between nominal and FSR. Two methods are tested to estimate the FSR effects; the first method uses a set of efficiency factors to represent the signal regions, the second method is to add a weight to the events of the nominal sample. The first method show positive results, especially in SR2, compared to a basic analysis, with an uncertainty of the FSR effect of: SR1:±29% SR2: ±51% SR3: ±37%. While a basic analysis gave an uncertainty of ±42%, ±122% and 36%. The second method shows positive signs where the re-weighted sample moves closer to the behaviour of the FSR sample. However, both methods are based on insufficient amount of statistics to draw any absolute conclusions.

Place, publisher, year, edition, pages
2011. , 51 p.
Trita-FYS, ISSN 0280-316X ; 2011:60
Keyword [en]
Particle physics, Supersymmetry, Systematic effects
National Category
Subatomic Physics
URN: urn:nbn:se:kth:diva-93450ISRN: KTH/FYS/--11:60--SEOAI: diva2:516126
Subject / course
Educational program
Master of Science in Engineering -Engineering Physics
Physics, Chemistry, Mathematics
Available from: 2012-05-10 Created: 2012-04-17 Last updated: 2012-05-10Bibliographically approved

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