Conformal invariance and particle aspects in general relativity

We study the breakdown of conformal symmetry in a conformally invariant gra vitational model. The symmetry breaking is introduced by defining a preferr ed conformal frame in terms of the large scale characteristics of the unive rse. In this context we show that a local change of the preferred conformal frame results in a Hamilton-Jacobi equation describing a particle with adj ustable mass. In this equation the dynamical characteristics of the particl e substantially depends on the applied conformal factor and local geometry. Relevant interpretations of the results are also discussed.