Measurements of Beauty Production Cross-Sections and Fragmentation Ratios using the LHCb Detector
Date of Award
Doctor of Philosophy (PhD)
Physical Sciences and Mathematics
The measurements of b-quark production cross-sections in 7 and 13 TeV proton-proton collisions, and b-flavored hadron fragmentation fraction ratios in 13 TeV proton-proton collisions are presented using data taken with the LHCb detector located on the Large Hadron Collider (LHC). Both measurements are essential components of precision studies of beauty quark decays, which aim at probing the Standard Model of elementary particles and their interactions and possibly uncover evidence for new physics in rare decays or CP-violation asymmetries. In the former measurement, the absolute production cross-sections are found to be consistent with next-to-leading-order (NLO) QCD calculations as a function of the pseudorapidity of the decaying b-hadron. The overall shape and normalization of the ratio between the cross-section measured at 7 and 13 TeV is in agreement with theoretical expectations. The latter measurement quantifies the kinematic dependence of the fragmentation fraction ratios of the strange b-meson and the b-flavored Lambda baryon, with respect to the sum of lighter b-mesons. The integrated ratio of the strange b-meson with respect to the sum of lighter b-mesons is the most precise single measurement to date. Additionally, measurements on (irradiated) prototype and production silicon micro-strip detectors for the LHCb Upstream Tracker (UT) upgrade are presented. These measurements are essential to the quality-assurance aspects of the UT project and provide a baseline measurement of irradiation properties for future radiation studies.
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Kelsey, Matthew, "Measurements of Beauty Production Cross-Sections and Fragmentation Ratios using
the LHCb Detector" (2018). Dissertations - ALL. 857.