Quantum corrected geodesics - art. no. 084018

We compute the graviton-induced corrections to the trajectory of a classica l test particle. We show that the motion of the test particle is governed b y an effective action given by the expectation value (with respect to the g raviton state) of the classical action. We analyze the quantum corrected eq uations of motion for the test particle in two particular backgrounds: a Ro bertson Walker spacetime and a (2 + 1)-dimensional spacetime with rotationa l symmetry. In both cases we show that the quantum corrected trajectory is not a geodesic of the background metric. [S0556-2821(99)09118-3].