Exclusive Production of Quarkonia and Generalized Parton Distributions

The understanding of the nucleon is as of yet not complete. In particular, the contribution of the gluon content is not well understood. Utilizing the framework of Generalized Parton Distributions enables predictions to be made if some information on them is known. We investigated exclusive photo and electroproduction of heavy vector mesons (the quarkonia J/ψ and ϒ), which can give access to the currently poorly constrained gluon distribution Eg. For this reason, we implemented a model for it with several variants in order to represent a spread of plausible distributions. We used current experimental results for exclusive φ and ρ0 production to test our variants for Eg. For quarkonium production, the analytic calculation of the Leading Order production amplitudes was performed, verifying results published previously, in particular confirming that in the non-relativistic collinear approximation there is no access to the polarized or gluon helicity flip distributions, i.e. Hg and HgT. Numerical results for both the Leading Order and, in the case of photoproduction, also Next-to-Leading Order amplitudes were calculated, based on our Leading Order amplitudes and already existing Next-to-Leading Order expressions. The observables we looked at are the unpolarized cross section, spin density matrix elements, and two spin-asymmetries --- the transverse single-spin asymmetry An, and a newly discussed double-spin asymmetry ALS, which we identified as a very promising observable for measuring Eg. We find that in the case of J/ψ photoproduction higher order corrections seem not well under control, while for ϒ production the numerical results become much more stable.

Grantor dc:publisher

Temple University. Libraries

Year dc:date.issued

2015

Author dc:creator

• Koempel, John Paul

Advisor dc:contributor.advisor

• Metz, Andreas

Committee members dc:contributor.committeemember

• Burkhardt, T. W. (Theodore W.), 1940-
• Meziani, Zein-Eddine
• Riseborough, Peter
• Gamberg, Leonard P.

• Physics
• Particle physics

Statement dc:rights

• IN COPYRIGHT- This Rights Statement can be used for an Item that is in copyright. Using this statement implies that the organization making this Item available has determined that the Item is in copyright and either is the rights-holder, has obtained permission from the rights-holder(s) to make their Work(s) available, or makes the Item available under an exception or limitation to copyright (including Fair Use) that entitles it to make the Item available.

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

eng

Dc Identifier Other

931912217

OAI identifier oai:identifier

oai:scholarshare.temple.edu:20.500.12613/3130