# Inclusive and differential measurements of spin correlation in top-antitop quark pairs at √s = 8 TeV using the ATLAS detector

Levy, Mark (2016). Inclusive and differential measurements of spin correlation in top-antitop quark pairs at √s = 8 TeV using the ATLAS detector. University of Birmingham. Ph.D.

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## Abstract

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.

Type of Work: Thesis (Doctorates > Ph.D.)
Award Type: Doctorates > Ph.D.
Supervisor(s):
Supervisor(s)EmailORCID
Watson, MiriamUNSPECIFIEDUNSPECIFIED
Hawkes, ChrisUNSPECIFIEDUNSPECIFIED
Licence:
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/6995

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