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We exhibit long-lived resonances in scattering from two-dimensional soft cage potentials comprised of three and four Gaussian peaks. Specific low-energy resonances with very narrow width are shown to correspond to classical multiple-reflection events. These states have much larger probability densities inside the cage than outside and mimic bound states in the sense that the symmetry-breaking effect of the incident wave is relatively small. As a result we have found that isolated states display the simple symmetry characteristics of bound states. Overlapping resonances exhibit a mixing of symmetry classes leading to wave functions of lower symmetry, like those of wider resonances at higher energy. We demonstrate that at energies below the lowest resonances of two-dimensional cages, where the distance across the entrance of the cage corresponds to less than half a wavelength, the wave function may still gain access to the interior region by squeezing its wavelength in the necessary direction at the expense of the kinetic energy in the direction normal to the opening. The resulting curvature of the wave function in the donor dimension corresponds to an imaginary wavenumber, curving away from the plane defined by zero amplitude. This mechanism for passing between obstacles may be relevant for electronic and optical devices having spatial structures with dimensions comparable to the wavelengths of the energy carriers. / Graduation date: 2005

We introduce a relativistic model for pion-nucleon scattering which includes an elementary delta dressed by its decay. Crossing-symmetric single-particle exchange is augmented by parametrized multiple-scattering interactions, with covariant sideways form factors in both 3- and 4-field vertices. Causality is enforced by dispersion relations. Unitary fits to observed on-shell amplitudes are obtained; a modest number of parameters precisely reproduce all 6 S- and P-wave ��-N amplitudes up to 1.36 GeV invariant mass. / Graduation date: 1995

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 151-164).

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 107-108). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 107-108). Also available on the Internet.

Thesis (Ph. D.)--University of Oregon, 2004. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 69-70). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

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