Doctor of Philosophy (Ph.D.)
Carl E Carlson
The production of high transverse momenta mesons via polarized photoproduction can be a means of determining the parton structure of the target. at the regions of highest transverse pion momenta, kT, it can be shown that short distance, direct, pion production dominates and is sensitive to the polarized quark distributions. as the produced pions transverse momenta decreases the importance of pions produced through fragmentation following photon-gluon fusion increases. This process give us sensitivity to the form of the polarized gluon distribution. Both processes are calculable with perturbative Quantum Chromodynamics (pQCD) due to the high kT of the pion produced. Numerical results are presented for conditions in current g1 experiments. In order to determine the region in which the kT is sufficient for the use of pQCD, and to separate the desired processes from unwanted background functions, a calculation of the soft processes is undertaken. Vector meson dominance is the largest contributor to the soft processes and can be large enough to make a measurement of the asymmetries susceptible to the polarized gluon distributions difficult at the kinematics of existing g1 experiments. Once all of the contributions are known I can use the above processes to extend Bloom-Giliman scaling and duality to semi-exclusive processes. It will be shown that the scaling behavior should exist for the direct process and that regions where this process is dominant do exist. I will also show that the constancy with changing momentum transfer of the resonance peak/scaling curve ratio, familiar for many resonances in deep inelastic scattering, is also expected in the semi-exclusive case.
© The Author
Wahlquist, Christian Jens, "Studies in hard pion photoproduction" (2000). Dissertations, Theses, and Masters Projects. Paper 1539623996.