The study of baryon resonances offers a deeper understanding of the strong interaction, since the dynamics and relevant degrees
of freedom hidden within them are reflected by the properties of these states. The baryon resonances have been fairly accurately predicted in
the low-energy region by constituent quark models and lattice quantum chromodynamics. However, most of the predicted higher-lying excited
resonances (center-of-mass energies above 1.7 GeV/c²) and experimental findings do not match up. The model calculations predict more baryon
resonances than have been experimentally observed. Quark model calculations have suggested that some of the unobserved resonances couple
strongly to γp reactions. The higher-lying excited are also generally predicted to have strong couplings to final states involving a heavier
meson, e.g. one of the vector mesons, ρ, ω, ϕ. The excited states of the nucleon are usually found as broadly overlapping resonances, which
may decay into a multitude of finasl states involving mesons and baryons. Polarization observables make it possible to isolate
singleresonance contributions from other interference terms. This works presents measurements of the helicity asymmetry, E, for the reaction
γp → pω in the energy range 1.1 GeV < Eγ < 2.3 GeV, differential cross sections, and spin density matrix elements, also for the
reaction γp → pω in the energy range 1.5 GeV < Eγ < 5.4 GeV. Photoproduction of nucleon resonances in their decay to strange particles
also offers attractive possibilities because the strange quark in the particle generates another degree of freedom and gives additional
information not available from the nucleon-nucleon scattering. Thus, we have also extracted the helicity asymmetry, E, for the reaction γp →
K⁰Σ⁺ in the energy range 1.1 GeV < Eγ < 2.1 GeV, differential cross sections, and recoil hyperon polarization, P, also for the reaction
γp → K⁰Σ⁺ in the energy range 1.15 GeV < Eγ < 3.0 GeV. The data were collected at Jefferson Lab, using the CLAS detector, as part of
the g9a and g12 experiments. Both experiments, as part of the N* spectroscopy program at Jefferson Laboratory, accumulated photoproduction
data using circularly-polarized photons incident on a longitudinally-polarized butanol target in the g9a experiment and un-polarized liquid
hydrogen target for the g12 experiment. A partial-wave analysis to the E data for the reaction γp → pω within the
Bonn-Gatchina framework found dominant contributions from the 3/2⁺ near threshold, which is identified with the sub-treshold N(1720)3/2⁺ resonance. Some additional resonances and the t-channel π and pomeron exchange are needed to describe the data. / A Dissertation submitted to the Department of Physics in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Summer Semester 2018. / July 10, 2018. / CLAS detector, Hadronic Physics, Jefferson Laboratory, Nucleon Resonances, Sigma-Hyperon photoproduction, vector-meson photoproduction / Includes bibliographical references. / Volker Crede, Professor Directing Dissertation; Anke Meyer-Baese, University Representative; Jorge Piekarewicz, Committee Member; Paul Eugenio, Committee Member; Todd Adams, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_647183 |
| Contributors | Akbar, Zulkaida (author), Crede, Volker (professor directing dissertation), Meyer-Bäse, Anke (university representative), Piekarewicz, Jorge (committee member), Eugenio, Paul Michael, 1966- (committee member), Adams, Todd (committee member), Florida State University (degree granting institution), College of Arts and Sciences (degree granting college), Department of Physics (degree granting departmentdgg) |
| Publisher | Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text, doctoral thesis |
| Format | 1 online resource (202 pages), computer, application/pdf |
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