Photoproduction of the π0 meson was studied using the CLAS detector at the Thomas Jefferson National Accelerator Facility using tagged incident photon energies spanning the range Eγ = 1.1 GeV - 5.45 GeV. The measurement is performed on a liquid hydrogen target in the reaction γp → pe +e–(γ). The final state of the reaction is the sum of two subprocesses for π0 decay, the Dalitz decay mode of π0 → e +e–γ and conversion mode where one photon from π0 → γγ decay is converted into a e+e – pair. This specific final state reaction avoided limitations caused by single prompt track triggering, while the span of incident photon energies allowed for measurements of π0 photoproduction to a domain never systematically measured before.
We report the measurement of the π0 differential cross sections dσ/dΩ and dσ/dt. The angular distributions agree well with the SAID parametrization for incident beam energies below 3 GeV. As a result with this new data, the χ2/p.d.f. of the global fit in the SAID parametrization improved to 3.1 from 3.7. For incident beam energies greater than 3 GeV a comparison of a model based on Generalized Parton Distributions (GPD) with experimental data shows significant discrepancy, requiring further model developments to describe the data.
","abstract_html":"<p>Photoproduction of the π<sup>0</sup> meson was studied using the CLAS detector at the Thomas Jefferson National Accelerator Facility using tagged incident photon energies spanning the range <em>E</em><sub>γ</sub> = 1.1 GeV - 5.45 GeV. The measurement is performed on a liquid hydrogen target in the reaction γ<em>p</em> → <em>pe</em> <sup>+</sup><em>e</em><sup>–</sup>(γ). The final state of the reaction is the sum of two subprocesses for π<sup>0</sup> decay, the Dalitz decay mode of π<sup>0</sup> → <em>e</em> <sup>+</sup><em>e</em><sup>–</sup>γ and conversion mode where one photon from π<sup>0</sup> → γγ decay is converted into a <em>e</em><sup>+</sup><em>e</em> – pair. This specific final state reaction avoided limitations caused by single prompt track triggering, while the span of incident photon energies allowed for measurements of π<sup>0</sup> photoproduction to a domain never systematically measured before.</p> <p>We report the measurement of the π<sup>0</sup> differential cross sections <em>dσ</em>/<em>dΩ</em> and <em>dσ</em>/<em>dt</em>. The angular distributions agree well with the SAID parametrization for incident beam energies below 3 GeV. As a result with this new data, the χ<sup>2</sup>/<em>p.d.f.</em> of the global fit in the SAID parametrization improved to 3.1 from 3.7. For incident beam energies greater than 3 GeV a comparison of a model based on Generalized Parton Distributions (GPD) with experimental data shows significant discrepancy, requiring further model developments to describe the data.</p>","abstract_has_math":false,"creators":["Kunkel, Michael C."],"institution":null,"degree_name":"Doctor of Philosophy (PhD)","degree_level":"Dissertation","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":["Moskov Amaryan","Ian Balitsky","Alexander Godunov","Chester Grosch","Lawrence Weinstein"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2014,"date_issued":"2014-01-01T08:00:00Z","date_published":"2014-01-01T08:00:00Z","updated_at":"2026-07-24T03:34:18Z","subjects":["1.2-5.45 GeV","CLAS","Cross Section","Neutral Pion","Photoproduction","Pion decay","Elementary Particles and Fields and String Theory","Nuclear"],"languages":[],"rights":["In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["9781321558654"],"render_values":[{"text":"9781321558654","href":null,"code":true}]}]},"links":{"outbound_url":"https://digitalcommons.odu.edu/physics_etds/54","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Moskov Amaryan","Ian Balitsky","Alexander Godunov","Chester Grosch","Lawrence Weinstein"]},{"key":"dc:creator","label":"Author","values":["Kunkel, Michael C."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2019-02-21T08:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Physics"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy (PhD)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["1.2-5.45 GeV","CLAS","Cross Section","Neutral Pion","Photoproduction","Pion decay","Elementary Particles and Fields and String Theory","Nuclear"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["9781321558654","https://digitalcommons.odu.edu/physics_etds/54"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Photoproduction of the π0 meson was studied using the CLAS detector at the Thomas Jefferson National Accelerator Facility using tagged incident photon energies spanning the range Eγ = 1.1 GeV - 5.45 GeV. The measurement is performed on a liquid hydrogen target in the reaction γp → pe +e–(γ). The final state of the reaction is the sum of two subprocesses for π0 decay, the Dalitz decay mode of π0 → e +e–γ and conversion mode where one photon from π0 → γγ decay is converted into a e+e – pair. This specific final state reaction avoided limitations caused by single prompt track triggering, while the span of incident photon energies allowed for measurements of π0 photoproduction to a domain never systematically measured before.
We report the measurement of the π0 differential cross sections dσ/dΩ and dσ/dt. The angular distributions agree well with the SAID parametrization for incident beam energies below 3 GeV. As a result with this new data, the χ2/p.d.f. of the global fit in the SAID parametrization improved to 3.1 from 3.7. For incident beam energies greater than 3 GeV a comparison of a model based on Generalized Parton Distributions (GPD) with experimental data shows significant discrepancy, requiring further model developments to describe the data.
"]},{"key":"dc:title","label":"Title","values":["Photoproduction of π0 on Hydrogen With CLAS From 1.1 GeV - 5.45 GeV Using e+e –γ Decay"]}]}],"canonical_facts":{"dc:contributor":["Moskov Amaryan","Ian Balitsky","Alexander Godunov","Chester Grosch","Lawrence Weinstein"],"dc:creator":["Kunkel, Michael C."],"dc:date.available":["2019-02-21T08:00:00Z"],"dc:description.abstract":["Photoproduction of the π0 meson was studied using the CLAS detector at the Thomas Jefferson National Accelerator Facility using tagged incident photon energies spanning the range Eγ = 1.1 GeV - 5.45 GeV. The measurement is performed on a liquid hydrogen target in the reaction γp → pe +e–(γ). The final state of the reaction is the sum of two subprocesses for π0 decay, the Dalitz decay mode of π0 → e +e–γ and conversion mode where one photon from π0 → γγ decay is converted into a e+e – pair. This specific final state reaction avoided limitations caused by single prompt track triggering, while the span of incident photon energies allowed for measurements of π0 photoproduction to a domain never systematically measured before.
We report the measurement of the π0 differential cross sections dσ/dΩ and dσ/dt. The angular distributions agree well with the SAID parametrization for incident beam energies below 3 GeV. As a result with this new data, the χ2/p.d.f. of the global fit in the SAID parametrization improved to 3.1 from 3.7. For incident beam energies greater than 3 GeV a comparison of a model based on Generalized Parton Distributions (GPD) with experimental data shows significant discrepancy, requiring further model developments to describe the data.
"],"dc:identifier":["9781321558654","https://digitalcommons.odu.edu/physics_etds/54"],"dc:rights":["In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
"],"dc:subject":["1.2-5.45 GeV","CLAS","Cross Section","Neutral Pion","Photoproduction","Pion decay","Elementary Particles and Fields and String Theory","Nuclear"],"dc:title":["Photoproduction of π0 on Hydrogen With CLAS From 1.1 GeV - 5.45 GeV Using e+e –γ Decay"],"thesis:degree_discipline":["Physics"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Doctor of Philosophy (PhD)"]},"updated_at":"2026-07-24T03:34:18Z"}