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Differential Top Quark Spin Correlations with the CMS Detector Not Yet Public

Reason: At the time of writing this dissertation, the results shown in this dissertation are not explicitly approved for public release by CMS and are to be regarded as private, in-progress work utilizing CMS recorded data and MC simulations. By the time the embargo on this dissertation has been lifted, the results shown in this dissertation will have been superseded by CMS public results.

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Top Quark Spin Correlations with the CMS Detector

thesis
posted on 2023-04-27, 20:21 authored by Jason R ThiemanJason R Thieman

This dissertation presents precision measurements of top quark polarizations and top quark pair spin correlations, which probe the independent coefficients of the top-spin components of the top quark pair production density matrix, targeting all channels (ee, eµ,  µµ) of the top quark pair dileptonic decay mode with final states containing two oppositely charged leptons, and using 137.7 fb⁻¹ of data recorded by the CMS experiment at the LHC with 13 TeV center-of-mass energy, during 2016, 2017, and 2018.

All measured observables are corrected for detector efficiencies, acceptances, and migrations, unfolded to parton-level, and extrapolated to the full phase space using a regularized unfolding procedure.

Spin-density coefficients are extracted from the unfolded distributions and compared to theoretical predictions and predictions from Monte Carlo simulations with next-to-leading-order matrix element accuracy interfaced with parton-shower algorithms.

The measurements are performed both in the full phase-space and differentially as a function of top quark pair invariant mass.

The measured coefficients showed decent agreement with the MC predictions, and better agreement when compared to QCD perturbative calculations for top quark pair production at NLO with electroweak corrections, and the measurement precision for one-dimensional normalized unfolded cross-sections and extracted coefficients were improved by as much as a factor of two compared to previous measurements.

Funding

DOE Grant #14000369 via Purdue University

History

Degree Type

  • Doctor of Philosophy

Department

  • Physics and Astronomy

Campus location

  • West Lafayette

Advisor/Supervisor/Committee Chair

Andreas Jung

Advisor/Supervisor/Committee co-chair

Matthew Jones

Additional Committee Member 2

Martin Kruczenski

Additional Committee Member 3

John Finley

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