{"id":{"repo_id":"cape-town","oai_identifier":"oai:open.uct.ac.za:11427/39976"},"canonical_url":"https://search.dev.ndltd.org/etd/cape-town/oai:open.uct.ac.za:11427/39976","repository":{"repo_id":"cape-town","name":"University of Cape Town","base_url":"https://open.uct.ac.za/oai/request"},"display":{"title":"Using the ¢-meson to probe the medium created in Au+Au collisons at RHIC","abstract":"[pg 76 is missing] This thesis presents measurements of ¢-meson production and elliptic flow, 1,2, with the aim of probing the characteristics of the medium created in ultra-relativistic nucleus-nucleus collisions. Using the decay channel q;-+ K+ K-, high statistics measurements have been made for ¢-meson production at mid-rapidity in Au+Au collisions at ,.,jsim = 200 GeV using the STAR detector at RHIC. The ¢-meson invariant yields both integrated, and as a function of PT, are presented for a wide range of collision centralities. The transverse momentum distributions exhibit an evolution in shape with decreasing collision centrality from exponential-like to power-law-like, indicating a variation in the relative contributions from competing particle production mechanisms to ¢ production as a function of collision centrality. Measurements of the nuclear modification factor, Rep, for 0-5% central relative to 40-60% and 60-80% central collisions show that binary-scaled ¢-meson production is suppressed in central compared to more peripheral collisions. The baryon-meson scaling of Rep observed for other identified particles is also observed for the ¢-meson through its similarity to the K� Rep for 0-5%/40-60% ratio. The scaling appears to break down in the 0- 5%/60-80% case. The centrality dependence of the N ( 0) / N ( ¢) ratios are also presented. The central ratio is consistent up to Pr ;S 4 Ge V / c with expectations from a model in which multistrange hadrons are produced predominantly by recombination of thermal s quarks. In addition, the ¢-meson elliptic flow, v2 (pr ), has been measured in Au+Au collisions at ,.,fsim = 62.4 GeV and 200 GeV and is found to be similar for the two collision energies. The significant v2 for the ¢-meson, comparable to that of other particles, indicates significant rescattering of the medium constituents. In minimum bias collisions at 200 GeV, for PT < 2 GeV /c, the ¢-meson v2 is consistent with a mass ordering expected from hydrodynamics while for PT > 2 Ge V / c it is consistent with meson-scaling. This is strong evidence for partonic collectivity of the medium created in the collisions. First measurements of the centrality dependence of the ¢-meson integrated elliptic flow scaled by the eccentricity of the nuclear overlap region, (v2) / Epart, show an increasing trend with centrality and may indicate greater collectivity of the medium created in central compared to peripheral Au+Au collisions.","abstract_html":"[pg 76 is missing] This thesis presents measurements of ¢-meson production and elliptic flow, 1,2, with the aim of probing the characteristics of the medium created in ultra-relativistic nucleus-nucleus collisions. Using the decay channel q;-+ K+ K-, high statistics measurements have been made for ¢-meson production at mid-rapidity in Au+Au collisions at ,.,jsim = 200 GeV using the STAR detector at RHIC. The ¢-meson invariant yields both integrated, and as a function of PT, are presented for a wide range of collision centralities. The transverse momentum distributions exhibit an evolution in shape with decreasing collision centrality from exponential-like to power-law-like, indicating a variation in the relative contributions from competing particle production mechanisms to ¢ production as a function of collision centrality. Measurements of the nuclear modification factor, Rep, for 0-5% central relative to 40-60% and 60-80% central collisions show that binary-scaled ¢-meson production is suppressed in central compared to more peripheral collisions. The baryon-meson scaling of Rep observed for other identified particles is also observed for the ¢-meson through its similarity to the K� Rep for 0-5%/40-60% ratio. The scaling appears to break down in the 0- 5%/60-80% case. The centrality dependence of the N ( 0) / N ( ¢) ratios are also presented. The central ratio is consistent up to Pr ;S 4 Ge V / c with expectations from a model in which multistrange hadrons are produced predominantly by recombination of thermal s quarks. In addition, the ¢-meson elliptic flow, v2 (pr ), has been measured in Au+Au collisions at ,.,fsim = 62.4 GeV and 200 GeV and is found to be similar for the two collision energies. The significant v2 for the ¢-meson, comparable to that of other particles, indicates significant rescattering of the medium constituents. In minimum bias collisions at 200 GeV, for PT &lt; 2 GeV /c, the ¢-meson v2 is consistent with a mass ordering expected from hydrodynamics while for PT &gt; 2 Ge V / c it is consistent with meson-scaling. This is strong evidence for partonic collectivity of the medium created in the collisions. First measurements of the centrality dependence of the ¢-meson integrated elliptic flow scaled by the eccentricity of the nuclear overlap region, (v2) / Epart, show an increasing trend with centrality and may indicate greater collectivity of the medium created in central compared to peripheral Au+Au collisions.","abstract_has_math":false,"creators":["Blyth, Sarah-Louise"],"institution":"Department of Physics","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2007,"date_issued":"2007","date_published":"2007","updated_at":"2026-07-22T22:23:29Z","subjects":["Physics"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/11427/39976","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Blyth, Sarah-Louise"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2024-06-19T10:14:30Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2024-06-19T10:14:30Z"]},{"key":"dc:date.issued","label":"Date","values":["2007"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Department of Physics"]},{"key":"dc:type","label":"Dc Type","values":["Thesis / Dissertation"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["Doctoral","PhD"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Physics"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/11427/39976"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["[pg 76 is missing] This thesis presents measurements of ¢-meson production and elliptic flow, 1,2, with the aim of probing the characteristics of the medium created in ultra-relativistic nucleus-nucleus collisions. Using the decay channel q;-+ K+ K-, high statistics measurements have been made for ¢-meson production at mid-rapidity in Au+Au collisions at ,.,jsim = 200 GeV using the STAR detector at RHIC. The ¢-meson invariant yields both integrated, and as a function of PT, are presented for a wide range of collision centralities. The transverse momentum distributions exhibit an evolution in shape with decreasing collision centrality from exponential-like to power-law-like, indicating a variation in the relative contributions from competing particle production mechanisms to ¢ production as a function of collision centrality. Measurements of the nuclear modification factor, Rep, for 0-5% central relative to 40-60% and 60-80% central collisions show that binary-scaled ¢-meson production is suppressed in central compared to more peripheral collisions. The baryon-meson scaling of Rep observed for other identified particles is also observed for the ¢-meson through its similarity to the K� Rep for 0-5%/40-60% ratio. The scaling appears to break down in the 0- 5%/60-80% case. The centrality dependence of the N ( 0) / N ( ¢) ratios are also presented. The central ratio is consistent up to Pr ;S 4 Ge V / c with expectations from a model in which multistrange hadrons are produced predominantly by recombination of thermal s quarks. In addition, the ¢-meson elliptic flow, v2 (pr ), has been measured in Au+Au collisions at ,.,fsim = 62.4 GeV and 200 GeV and is found to be similar for the two collision energies. The significant v2 for the ¢-meson, comparable to that of other particles, indicates significant rescattering of the medium constituents. In minimum bias collisions at 200 GeV, for PT < 2 GeV /c, the ¢-meson v2 is consistent with a mass ordering expected from hydrodynamics while for PT > 2 Ge V / c it is consistent with meson-scaling. This is strong evidence for partonic collectivity of the medium created in the collisions. First measurements of the centrality dependence of the ¢-meson integrated elliptic flow scaled by the eccentricity of the nuclear overlap region, (v2) / Epart, show an increasing trend with centrality and may indicate greater collectivity of the medium created in central compared to peripheral Au+Au collisions."]},{"key":"dc:title","label":"Title","values":["Using the ¢-meson to probe the medium created in Au+Au collisons at RHIC"]}]}],"canonical_facts":{"dc:creator":["Blyth, Sarah-Louise"],"dc:date.accessioned":["2024-06-19T10:14:30Z"],"dc:date.available":["2024-06-19T10:14:30Z"],"dc:date.issued":["2007"],"dc:description.abstract":["[pg 76 is missing] This thesis presents measurements of ¢-meson production and elliptic flow, 1,2, with the aim of probing the characteristics of the medium created in ultra-relativistic nucleus-nucleus collisions. Using the decay channel q;-+ K+ K-, high statistics measurements have been made for ¢-meson production at mid-rapidity in Au+Au collisions at ,.,jsim = 200 GeV using the STAR detector at RHIC. The ¢-meson invariant yields both integrated, and as a function of PT, are presented for a wide range of collision centralities. The transverse momentum distributions exhibit an evolution in shape with decreasing collision centrality from exponential-like to power-law-like, indicating a variation in the relative contributions from competing particle production mechanisms to ¢ production as a function of collision centrality. Measurements of the nuclear modification factor, Rep, for 0-5% central relative to 40-60% and 60-80% central collisions show that binary-scaled ¢-meson production is suppressed in central compared to more peripheral collisions. The baryon-meson scaling of Rep observed for other identified particles is also observed for the ¢-meson through its similarity to the K� Rep for 0-5%/40-60% ratio. The scaling appears to break down in the 0- 5%/60-80% case. The centrality dependence of the N ( 0) / N ( ¢) ratios are also presented. The central ratio is consistent up to Pr ;S 4 Ge V / c with expectations from a model in which multistrange hadrons are produced predominantly by recombination of thermal s quarks. In addition, the ¢-meson elliptic flow, v2 (pr ), has been measured in Au+Au collisions at ,.,fsim = 62.4 GeV and 200 GeV and is found to be similar for the two collision energies. The significant v2 for the ¢-meson, comparable to that of other particles, indicates significant rescattering of the medium constituents. In minimum bias collisions at 200 GeV, for PT < 2 GeV /c, the ¢-meson v2 is consistent with a mass ordering expected from hydrodynamics while for PT > 2 Ge V / c it is consistent with meson-scaling. This is strong evidence for partonic collectivity of the medium created in the collisions. First measurements of the centrality dependence of the ¢-meson integrated elliptic flow scaled by the eccentricity of the nuclear overlap region, (v2) / Epart, show an increasing trend with centrality and may indicate greater collectivity of the medium created in central compared to peripheral Au+Au collisions."],"dc:identifier.uri":["http://hdl.handle.net/11427/39976"],"dc:publisher.department":["Department of Physics"],"dc:subject":["Physics"],"dc:title":["Using the ¢-meson to probe the medium created in Au+Au collisons at RHIC"],"dc:type":["Thesis / Dissertation"],"dc:type.qualificationlevel":["Doctoral","PhD"]},"updated_at":"2026-07-22T22:23:29Z"}