Large massive 4d particle with torsion and conformal mechanics

The consequences of the coupling of the torsion (highest curvature) term to the Lagrangian of a massive spinless particle in four-dimensional space time are studied. It is shown that the modified system remains spinless and possesses extended gauge invariance. Though the torsion term does not generate spin, it provides the system with a nontrivial mass spectrum, described by one-dimensional conformal mechanics. Under an appropriate choice of characteristic constants the system has solutions with a discrete mass spectrum.