Covariant chronogeometry and extreme distances: Elementary particles.

We study a variant of elementary particle theory in which Minkowski space, M(0), is replaced by a natural alternative, the unique four-dimensional manifold M with comparable properties of causality and symmetry. Free particles are considered to be associated (i) with positive-energy representations in bundles of prescribed spin over M of the group of causality-preserving transformations on M (or its mass-conserving subgroup) and (ii) with corresponding wave equations. In this study these bundles, representations, and equations are detailed, and some of their basic features are developed in the cases of spins 0 and (1/2).

Symmetry and causality properties of physical fields.

Representations of groups of causality-preserving transformations on locally Minkowskian space-times, by actions on classes of wave functions of designated transformation properties, are analyzed, in extension of the conventional theoretical treatment of free relativistic particles. In particular, the constraints of positivity of the energy and finiteness of propagation velocity are developed, and the concept of mass is explored, within the indicated framework.