  Centaurs are objects whose orbits are found between those of the giant
planets. They are supposed to originate mainly from the TransNeptunian objects,
and they are among the sources of NearEarth Objects.TransNeptunian Objects
(TNOs) cross Neptune's orbit and produce the Centaurs. We investigate their
interactions with main belt asteroids to determine if chaotic scattering caused
by close encounters and impacts by these bodies may have played a role in the
dynamical evolution of the main belt. We find that Centaurs and TNOs that reach
the inner Solar System can modify the orbits of main belt asteroids, though
only if their mass is of the order of 1 billion less the mass of the sun for
single encounters or, one order less in the case of multiple close encounters.
Centaurs and TNOs are unlikely to have significantly dispersed young asteroid
families in the main belt, but they can have perturbed some old asteroid
families. Current main belt asteroids that originated as Centaurs or
Trans-Neptunian Objects may lie in the outer belt with short lifetime less than
4 My, most likely between 2.8 au and 3.2 au at larger eccentricities than
typical of main belt asteroids.
