PROPAGATING TORSION FROM FIRST PRINCIPLES

A propagating torsion model is derived from the requirement of compati bility between minimal action principle and minimal coupling procedure in Riemann-Cartan spacetimes. In the proposed model, the trace of the torsion tensor is derived from a scalar potential that determines the volume element of the spacetime. The equations of the model are writt en down for the vacuum and for various types of matter fields. Some of their properties are discussed. In particular, we show that gauge fie lds can interact minimally with the torsion without the breaking of ga uge symmetry.