Phase structure and graviton propagators in lattice formulations of four-dimensional quantum gravity

We examine the phase structure of standard Regge calculus in four dimension s and compare our Monte Carlo results with those of the Zz-Regge model as w ell as with another formulation of lattice gravity derived from group-theor etical considerations. Within all of the three models of quantum gravity we find an extension of the well-defined phase to negative gravitational coup lings and a new phase transition. In contrast to the well known transition at positive coupling there is evidence for a continuous phase transition wh ich is essential for a continuum limit. We calculate two-point functions be tween geometrical quantities at the corresponding critical point and estima te the masses of the respective interaction particles.