Measurement of Semileptonic B Decays and Global Fits of Leptoquark Models

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dc.contributor.advisorJackson, Paul
dc.contributor.advisorWhite, Martin
dc.contributor.authorGrace, Philip
dc.contributor.schoolSchool of Physics, Chemistry and Earth Sciencesen
dc.date.issued2023
dc.description.abstractFlavour physics offers some of the most promising hints of physics beyond the Standard Model (BSM). Precision measurements in the last decade have shown significant deviations from SM predictions, which have been found to favour particular BSM interpretations. This work contributes to two aspects of the ongoing quest for deeper understanding of flavour physics: precision measurements of rare processes at the Belle II experiment, and global fits with flavour constraints in order to make conclusions about specific BSM models. The Full Event Interpretation (FEI) is a novel tagging algorithm developed by the Belle II collaboration. Here we demonstrate the use of the semileptonic FEI via a normalisation mode approach, which circumvents the ongoing difficulties in calibrating the semileptonic FEI. We use this approach to extract |𝑉𝑢𝑏|, obtaining a result that is consistent with world averages and has an uncertainty of 7% that is statistically dominated. There are avenues for improving the semileptonic FEI tagging in the future, and the statistical uncertainty may be greatly reduced with larger datasets. Anomalous measurements may be placed in a broader context by performing global fits. This allows us to map the high-dimensional parameter spaces of BSM models and determine which regions are favoured by all available results. This thesis presents preliminary results of a global fit of leptoquark models with a selection of flavour constraints, and investigates the viability of observing the non-excluded models at the LHC. We focus in particular on identifying regions of the parameter space which are still viable in light of the recent 𝑅(𝐾 (∗)) measurement by LHCb, which removes a previous long-standing anomaly. This thesis also details software work done regarding Belle II’s skimming procedure. This work helps to prepare Belle II for future data collection, when an optimised data processing pipeline will be critically necessary.en
dc.description.dissertationThesis (Ph.D.) -- University of Adelaide, School of Physics, Chemistry and Earth Sciences, 2023en
dc.identifier.urihttps://hdl.handle.net/2440/139549
dc.language.isoenen
dc.provenanceThis electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legalsen
dc.subjectBelle IIen
dc.subjectflavour physicsen
dc.subjectB mesonsen
dc.subjectsemileptonic decaysen
dc.subjectGAMBITen
dc.subjectleptoquarksen
dc.titleMeasurement of Semileptonic B Decays and Global Fits of Leptoquark Modelsen
dc.typeThesisen

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