Collins, Neil J (2011). A study of tau lepton production in tt events with ATLAS at the LHC. University of Birmingham. Ph.D.
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Collins_11_PhD.pdf
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Abstract
A method is discussed for measuring the tt cross section from tau + jets events in early ATLAS data. Multivariant techniques were avoided in favour of simple cuts and the analysis was applied to 26.4pb\(^-\)\(^1\)of 2010 data. A cut and count technique was used to estimate the number of tt events in a window around the hadronic top mass peak. Subtraction of QCD background from data was performed by scaling events from a QCD enriched sample by the ratio of events in a sideband region. With the current dataset a statistical error is expected of the order of 400% and a measurement is not feasible at this stage. The systematic error on the tt selection eciency was estimated to be 50%. Simple luminosity scaling established that a measurement should become possible within the 2011-2013 LHC run. Once ATLAS has collected between 1 fb\(^-\)\(^1\) and 3 fb\(^-\)\(^1\) of data a fractional error of 20% on the expected number of signal events could be achieved. Suggestions are made for reducing the systematic uncertainty on the tt eciency.
Type of Work: | Thesis (Doctorates > Ph.D.) | ||||||
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Award Type: | Doctorates > Ph.D. | ||||||
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College/Faculty: | Colleges (2008 onwards) > College of Engineering & Physical Sciences | ||||||
School or Department: | School of Physics and Astronomy | ||||||
Funders: | Science and Technology Facilities Council | ||||||
Subjects: | Q Science > QC Physics | ||||||
URI: | http://etheses.bham.ac.uk/id/eprint/1746 |
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