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A study of tau lepton production in tt events with ATLAS at the LHC

Collins, Neil J (2011)
Ph.D. thesis, University of Birmingham.

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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:Ph.D. thesis.
Supervisor(s):Watson, Alan
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:School of Physics and Astronomy
Subjects:QC Physics
Institution:University of Birmingham
ID Code:1746
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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