NOVEL GEOMETRIC GAUGE-INVARIANCE OF AUTOPARALLELS

We draw attention to a novel type of geometric gauge invariance relati ng the autoparallel equations of motion in different Riemann-Cartan sp acetimes with each other. The novelty lies in the fact that the equati ons of motion are invariant even though the actions are not. As an app lication we use this gauge transformation to map the action of a spinl ess point particle in a Riemann-Cartan spacetime with a gradient torsi on to a purely Riemann spacetime, in which the initial torsion appears as a nongeometric external field. By extremizing the transformed acti on in the usual way, we obtain the same autoparallel equations of moti on as those derived in the initial space time with torsion via a recen tly-discovered variational principle.