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Title: Inclusive and differential measurements of spin correlation in top-antitop quark pairs at √s = 8 TeV using the ATLAS detector
Author: Levy, Mark
ISNI:       0000 0004 5994 4241
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 2016
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A measurement of the spin correlation strength in top-antitop pairs is presented, using protonproton collision data collected at the ATLAS detector with a centre of mass energy of √s = 8 TeV and an integrated luminosity of 20.3 fb\(^{-1}\). An inclusive measurement is made, as well as a differential measurement as a function of the top-antitop invariant mass. Additionally, these measurements are made both at detector level and unfolded to a parton level distribution. Selected events are required to have exactly two oppositely charged leptons (either electrons or muons), a large missing transverse energy and at least two hadronic jets, at least one of which must be tagged as originating from a b-quark. The azimuthal separation between the two charged leptons, Δφ, is used to measure the degree of spin correlation. The measured distribution is compared to a Standard Model prediction and a model with no spin correlation. It is found that the results all favour the Standard Model prediction over the uncorrelated model, with the data found to be several standard deviations away from the uncorrelated scenario.
Supervisor: Not available Sponsor: Science and Technology Facilities Council (STFC)
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QC Physics