Photoproduction of π0 on Hydrogen With CLAS From 1.1 GeV - 5.45 GeV Using e+e –γ Decay

<p>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 <em>E</em>_γ = 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> ⁺<em>e</em>^–(γ). The final state of the reaction is the sum of two subprocesses for π⁰ decay, the Dalitz decay mode of π⁰ → <em>e</em> ⁺<em>e</em>^–γ and conversion mode where one photon from π⁰ → γγ decay is converted into a <em>e</em>⁺<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 π⁰ photoproduction to a domain never systematically measured before.</p> <p>We report the measurement of the π⁰ 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 χ²/<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>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Year dc:date.available

2014

Author dc:creator

• Kunkel, Michael C.

Contributors dc:contributor

• Moskov Amaryan
• Ian Balitsky
• Alexander Godunov
• Chester Grosch
• Lawrence Weinstein

• 1.2-5.45 GeV
• CLAS
• Cross Section
• Neutral Pion
• Photoproduction
• Pion decay
• Elementary Particles and Fields and String Theory
• Nuclear

Statement dc:rights

• <p>In Copyright. URI: <a href="http://rightsstatements.org/vocab/InC/1.0/">http://rightsstatements.org/vocab/InC/1.0/</a> 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).</p>

Identifier

9781321558654

OAI identifier oai:identifier

oai:digitalcommons.odu.edu:physics_etds-1060