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Title: A study of tau lepton production in tt events with ATLAS at the LHC
Author: Collins, Neil J.
ISNI:       0000 0004 2703 9079
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 2011
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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.
Supervisor: Not available Sponsor: STFC
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QC Physics