The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
Aalto

Top-Quark Mass Measurement

Tuula Mäki

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Faculty of Information and Natural Sciences for public examination and debate in Auditorium K215 at Helsinki University of Technology (Espoo, Finland) on the 18th of March, 2008, at 12 noon.

Overview in PDF format (ISBN 978-952-10-3715-3)   [510 KB]
Dissertation is also available in print (ISBN 978-952-10-3714-6)

Abstract

The top quark is the heaviest elementary particle. Its mass is one of the fundamental parameters of the standard model of particle physics, and an important input to precision electroweak tests.

This thesis describes three measurements of the top-quark mass in the dilepton decay channel. The dilepton events have two neutrinos in the final state; neutrinos are weakly interacting particles that cannot be detected with a multipurpose experiment. Therefore, the signal of dilepton events consists of a large amount of missing energy and momentum carried off by the neutrinos.

The top-quark mass is reconstructed for each event by assuming an additional constraint from a top mass independent distribution. Template distributions are constructed from simulated samples of signal and background events, and parametrized to form continuous probability density functions. The final top-quark mass is derived using a likelihood fit to compare the reconstructed top mass distribution from data to the parametrized templates. One of the analyses uses a novel technique to add top mass information from the observed number of events by including a cross-section-constraint in the likelihood function. All measurements use data samples collected by the CDF II detector.

This thesis consists of an overview and of the following 6 publications:

  1. A. Abulencia et al. with Tuula Maki (CDF Collaboration), 2006, Measurement of the top quark mass using template methods on dilepton events in pp̅  collisions at √s̅ = 1.96 TeV, Physical Review D, volume 73, 112006. © 2006 American Physical Society. By permission.
  2. A. Abulencia et al. with Tuula Maki (CDF Collaboration), 2006, Top-quark mass measurement from dilepton events at CDF II, Physical Review Letters, volume 96, 152002. © 2006 American Physical Society. By permission.
  3. T. Aaltonen et al. with Tuula Maki (CDF Collaboration), 2008, Cross-section-constrained top-quark mass measurement from dilepton events at the Tevatron, Physical Review Letters, volume 100, 062005. © 2008 American Physical Society. By permission.
  4. Tuula Maki on behalf of the CDF Collaboration, 2007, Status and performance of the CDF Run II silicon detector, Nuclear Instruments and Methods in Physics Research A, volume 579, pages 723-725. © 2007 Elsevier Science. By permission.
  5. Tuula Mäki on behalf of the CDF and DØ Collaborations, 2006, Measurement of the top quark mass in the dilepton channel at CDF and DØ, In: Peter D. Barnes et al. (editors), Proceedings of the 17th International Conference on Particles and Nuclei (PANIC 2006), Santa Fe, New Mexico, USA, 23-30 October 2005, AIP Conference Proceedings, volume 842, pages 625-627, ISBN 0-7354-0338-4. © 2006 American Institute of Physics. By permission.
  6. Tuula Maki on behalf of the CDF Collaboration, 2008, Top quark mass measurements at CDF, In: Roger Barlow (editor), Proceedings of the 2007 Europhysics Conference on High Energy Physics (HEP 2007), Manchester, England, 19-25 July 2007, Journal of Physics: Conference Series, accepted for publication. © 2008 Institute of Physics Publishing. By permission.

Keywords: top quark, particle physics, standard model, dilepton, CDF

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© 2008 Helsinki University of Technology

Last update 2011-05-26