Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607217
Title: Measurements of the χc and χb quarkonium states in ρρ collisions with the ATLAS experiment
Author: Chisholm, Andrew Stephen
ISNI:       0000 0004 5362 5864
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 2014
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Abstract:
The chi_b bottomonium states are observed through the reconstruction of the radiative decays chi_b(nP)→Upsilon(1S) gamma using 4.4/fb of pp collision data collected at sqrt(s) = 7 TeV with the ATLAS experiment. The production of the chi_b(1P) and chi_b(2P) bottomonium states is observed in addition to a candidate for a new bottomonium state, consistent with theoretical expectations for the chi_b(3P) states. The production-averaged mass barycentre for the chi_b(3P) candidate is measured to be 10541$$\pm$$11 (stat.) $$\pm$$ 30 (syst.) MeV. The consequences of this discovery for our understanding of bottomonium production phenomenology in hadronic collisions is reviewed. The production of the chi_c1 and chi_c2 charmonium states has been measured in sqrt(s) = 7 TeV pp collisions with the ATLAS experiment using a data sample representing an integrated luminosity of 4.5/fb. The prompt and non-prompt production cross sections for the chi_c1 and chi_c2 states are measured within the region | y(J/psi)| < 0.75. These measurements suggest that 24-28% of prompt J/psi are produced in feed-down from radiative chi_c1 and chi_c2 decays. The production of the chi_c2 state, relative to the chi_c1 state, is measured for both prompt and non-prompt production processes. This collection of measurements is compared to a number of theoretical predictions for chi_cJ production at the LHC. The branching fraction B(B$$\pm$$→chi_c1 K$$\pm$$) = (4.9$$_pm$$$$\pm$$ (stat.) $$\pm$$0.6 (syst.))x 10^-4 is also measured with the same dataset and chi_c event selection.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.607217  DOI: Not available
Keywords: QC Physics
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