Photoproduction of Pseudoscalar Mesons from Nuclei

Abstract

The subject of this doctoral study is the pseudoscalar meson photoproduction from nuclei. Two types of processes are investigated in this regard: coherent and quasifree processes. In the case of the coherent process, we study it for the photoproduction of pion and eta mesons. We place special emphasis on the various sources that put into question earlier nonrelativistic-impulse-approximation calculations. These include: final-state interactions, relativistic effects, off-shell ambiguities, and violations to the impulse approximation. By far the largest uncertainty emerges from the ambiguity in extending the many on-shell-equivalent representations of the elementary amplitude off the mass shell. In the case of the quasifree process, we study it for the photoproduction of the kaon meson. We compute the recoil polarization of the lambda-hyperon and the photon asymmetry as well as the differential cross section. By introducing the notion of a ``bound-nucleon propagator'' we exploit Feynman's trace techniques to develop closed-form, analytic expressions for all photoproduction observables. Our results indicate that polarization observables are sensitive only to the fundamental physics, making them ideal tools for the study of modifications to the elementary process in the nuclear medium.