The cosmological constant is historically reviewed from its introduction in classical and relativistic cosmology through its modern quantum guise where it appears as a vacuum energy density. Limits on the empirical value are in glaring contradiction to the expectations of field theoretical calculations. / Motivated by the natural connection between dilatation invariance and the extinction of the vacuum energy density, a phenomenological realization of a global scale symmetry is constructed. A complete treatment of such a realization in the context of a supergravitational toy model is calculated to one loop using an effective potential formalism. Particular attention is paid to the quantization of both supersymmetric and general coordinate gauges and to the concomitant ghost structure since traditional treatments have introduced non-local operators in the ghost Lagrangian and generating functional. Contributions to the effective potentid from the gravity sector are thus determined that contradict the literature. A particular class of tree-level scalar potentials that includes the 'no-scale' case is studied in the that space limit. While it is found that scale invariance can be maintained at the one-loop level and the cosmological constant made to vanish for all potentials in the class this is directly attributable to supersymmetry. A richer form of the Kahler potential or an enlarged particle content may facilitate the breaking of supersymmetry. / Phenomenological consequences of supergravity are investigated through a one-loop calculation of the electromagnetic form factor of the gravitino. Should such a form factor exist a signature of the gravitino might be found in processes with unlabeled products such as $e sp+e sp- to nothing.$ It is found that the form factor vanishes to this order, the Lorentz structures generated being too impoverished to withstand a constraining set of polarization conditions. / Finally the wormhole solution to the cosmological constant problem is examined in a semiclassical approximation. The notion that scalar field worm-holes must have associated conserved charges is questioned and a model of massive scalar field wormholes is delineated and proven to provide a counterexample. As the model allows baby universes nucleated with a certain eigenvalue of the scalar field momentum to classically evolve to a different value, competing semiclassical paths contribute to the same transition amplitude. Numerical simulations demonstrate that the novel semiclassical paths available to massive solutions cannot be overlooked in approximating the tunneling amplitude.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.39926 |
| Date | January 1995 |
| Creators | Hagan, Scott |
| Contributors | Burgess, C. P. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Physics.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001485373, proquestno: NN12393, Theses scanned by UMI/ProQuest. |
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