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Investigation of certain fundamental invariance properties of field theories including gravitational theories with torsion

Thesis/Dissertation ·
OSTI ID:6144658
We examine the scale-invariant Lagrangian densities in Riemannian and non-Riemannian spacetimes. We find that the most general scale-invariant Lagrangian density of a Riemann-Cartan spacetime can also be reduced in a manner similar to that demonstrated earlier by Lanczos for the Riemannian case. However, this type of reduction process is not possible in a non-metric spacetime. Duality transformations of the type defined in electromagnetic theory are discussed and classified in terms of those transformations having a direct relationship to an internal symmetry structure of a given gauge theory and those that do not. We show that to build a satisfactory generalized electromagnetic type theory with local duality invariance into a gauge theory, as at least a part of its internal symmetry structure, requires a group no smaller than SO/sub 3/ or (SU/sub 2/). By considering a special metric geometry with torsion (U/sub 4/) we can describe the duality vector field of a duality invariant Maxwell theory in terms of a special form of torsion. This result indicates that the special U/sub 4/ geometry could play a role in the already unified field theory of Rainich, Misner, and Wheeler (RMW). We show how one could express the RMW conditions, together with their immediate generalizations in terms of geometric objects of the special U/sub 4/ theory. Conformal and projective transformations on the U/sub 4/ connection are examined. It is shown that an appropriate combination of these transformations have the effect of producing a special type of projective transformation on a metric connection with torsion. In the context of a gauge theory based on a U/sub 4/ spacetime, this special type of projective invariance has been interpreted as the underlying invariance principle for baryon number conservation in the same way that gauge changes on the Maxwell vector potential relate to charge conservation.
Research Organization:
North Carolina State Univ., Raleigh (USA)
OSTI ID:
6144658
Country of Publication:
United States
Language:
English