Top-quark mass measurement

dc.contributorAalto-yliopistofi
dc.contributorAalto Universityen
dc.contributor.authorMäki, Tuula
dc.contributor.departmenten
dc.contributor.departmentfi
dc.contributor.schoolFaculty of Information and Natural Sciencesen
dc.contributor.schoolInformaatio- ja luonnontieteiden tiedekuntafi
dc.date.accessioned2012-02-24T09:04:34Z
dc.date.available2012-02-24T09:04:34Z
dc.date.issued2008-03-18
dc.description.abstractThe 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.en
dc.description.abstractTop-kvarkki on raskain hiukkanen, jolla ei ole sisäistä rakennetta. Sen massa on yksi hiukkasfysiikan perusteorian, standardimallin, tärkeimmistä parametreista, ja lisäksi top-kvarkin massan avulla pystytään ennustamaan Higgsin bosonin massa. Tämä väitöskirja käsittelee top-kvarkin massan mittaamista hajoamiskanavassa, jossa lopputila sisältää kaksi neutriinoa. Neutriinot vuorovaikuttavat hyvin heikosti materian kanssa, joten niitä ei voida järjestelmällisesti havaita hiukkasilmaisimilla. Näin ollen top-kvarkin massaa ei pystytä suoraan laskemaan tällaisten top-kvarkkikandidaattien mitatuista hajoamistuotteista. Käyttämällä hyväksi muuttujaa, jonka jakauma ei riipu top-kvarkin massasta, jokaiselle valintakriteerit täyttävälle top-kvarkkikandidaatille pystytään arvioimaan massa. Puuttuvasta tiedosta ja mitattujen parametrien epätarkkuuksista johtuen saatu massajakauma ei piikity todellisen top-kvarkin massan kohdalle, joten mallinnetusta datasta luodaan mallijakaumat. Mitattu top-kvarkin massa saadaan vertaamalla datasta saatua jakaumaa mallijakaumiin. Yksi mittauksista yhdistää menetelmään top-kvarkkikandidaattien lukumäärästä saadun tiedon top-kvarkin massasta. Kaikki mittaukset käyttävät CDF-kokeen mittaamaa dataa.fi
dc.description.versionrevieweden
dc.format.extent33, [app]
dc.format.mimetypeapplication/pdf
dc.identifier.isbn978-952-10-3715-3
dc.identifier.issn1455-0563
dc.identifier.urihttps://aaltodoc.aalto.fi/handle/123456789/3004
dc.identifier.urnurn:nbn:fi:tkk-011327
dc.language.isoenen
dc.publisherHelsinki University of Technologyen
dc.publisherTeknillinen korkeakoulufi
dc.relation.haspartA. 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. [article1.pdf] © 2006 American Physical Society. By permission.
dc.relation.haspartA. 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. [article2.pdf] © 2006 American Physical Society. By permission.
dc.relation.haspartT. 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. [article3.pdf] © 2008 American Physical Society. By permission.
dc.relation.haspartTuula 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. [article4.pdf] © 2007 Elsevier Science. By permission.
dc.relation.haspartTuula 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. [article5.pdf] © 2006 American Institute of Physics. By permission.
dc.relation.haspartTuula 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. [article6.pdf] © 2008 Institute of Physics Publishing. By permission.
dc.relation.ispartofseriesInternal report / Helsinki Institute of Physicsen
dc.relation.ispartofseries2008-01en
dc.subject.keywordtop quarken
dc.subject.keywordparticle physicsen
dc.subject.keywordstandard modelen
dc.subject.keyworddileptonen
dc.subject.keywordCDFen
dc.subject.otherPhysicsen
dc.titleTop-quark mass measurementen
dc.typeG5 Artikkeliväitöskirjafi
dc.type.dcmitypetexten
dc.type.ontasotVäitöskirja (artikkeli)fi
dc.type.ontasotDoctoral dissertation (article-based)en
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local.aalto.digifolderAalto_63499
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