J. Riedler

The Well defined phase of simplicial quantum gravity in four-dimensions

We analyze simplicial quantum gravity in four dimensions using the Regge approach. The existence of an entropy dominated phase with small negative curvature is investigated in detail. It turns out that observables of the system possess finite expectation values although the Einstein-Hilbert action is unbounded. This well-defined phase is found to be stable for a one-parameter family of measures. A preliminary study indicates that the influence of the lattice size on the average curvature is small. We compare our results with those obtained by dynamical triangulation and find qualitative correspondence.

Correlation functions in lattice formulations of quantum gravity

Abstract We compare different models of a quantum theory of four-dimensional lattice gravity based on Regges original proposal. From Monte Carlo simulations we calculate two-point functions between geometrical quantities and estimate the masses of the corresponding interaction particles.

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

We examine the phase structure of standard Regge calculus in four dimensions and compare our Monte Carlo results with those of the -Regge model as well as with another formulation of lattice gravity derived from group-theoretical considerations. Within all of the three models of quantum gravity we find an extension of the well-defined phase to negative gravitational couplings and a new phase transition. In contrast to the well known transition at positive coupling there is evidence for a continuous phase transition which is essential for a continuum limit. We calculate two-point functions between geometrical quantities at the corresponding critical point and estimate the masses of the respective interaction particles.

Z2-Regge versus Standard Regge Calculus in Two Dimensions

We consider two versions of quantum Regge calculus: the standard Regge calculus where the quadratic link lengths of the simplicial manifold vary continuously and the

Gravitational action versus entropy on simplicial lattices in four dimensions

{Z}_{2}

Signal confidence limits from a neural network data analysis

Regge model where they are restricted to two possible values. The goal is to determine whether the computationally more easily accessible

The phase structure of pure Regge gravity

{Z}_{2}

Phase diagram of Regge quantum gravity coupled to SU(2) gauge theory

model still retains the universal characteristics of standard Regge theory in two dimensions. In order to compare observables such as the average curvature or Liouville field susceptibility, we use in both models the same functional integration measure, which is chosen to render the

Static quark potentials in quantum gravity

{Z}_{2}

Two-point functions of four-dimensional simplicial quantum gravity

Regge model particularly simple. Expectation values are computed numerically and agree qualitatively for positive bare couplings. The phase transition within the