Quantum gravity coupled to scalar massive matter fields is investigated within the framework of causal perturbation theory. One-loop calculations include matter loop graviton self-energy and matter self-energy and yield ultraviolet finite and cutoff-free expressions. Perturbative gauge invariance to second order implies the usual Slavnov–Ward identities for the graviton self-energy in the loop ...

It has recently been shown that the Matrix model and supergravity give the same predictions for three graviton scattering. This contradicts an earlier claim in the literature. We explain the error in this earlier work, and go on to show that certain terms in the n-graviton scattering amplitude involving v are given correctly by the Matrix model. The Matrix model also generates certain v terms i...

We investigate the relation of the mass of the graviton to the number of information N in a flat universe. As a result we find that the mass of the graviton scales as [Formula: see text]. Furthermore, we find that the number of gravitons contained inside the observable horizon is directly proportional to the number of information N; that is, N gr ∝ N. Similarly, the total mass of gravitons that...

The technology required for eikonal scattering amplitude calculations in Matrix theory is developed. Using the entire supersymmetric completion of the v/r Matrix theory potential we compute the graviton–graviton scattering amplitude and find agreement with eleven dimensional supergravity at tree level.

We study graviton-graviton scattering in partial-wave amplitudes after unitarizing their Born terms. In order to apply S-matrix techniques, based on unitarity and analyticity, we introduce an associated this resummation that is free of infrared divergences. This achieved by removing the diverging phase factor calculated Weinberg multiplies S matrix, stems from virtual gravitons. A scalar resona...

If the graviton possesses an arbitrarily small (but nonvanishing) mass, perturbation theory implies that cosmic strings have a nonzero Newtonian potential. Nevertheless in Einstein gravity, where the graviton is strictly massless, the Newtonian potential of a cosmic string vanishes. This discrepancy is an example of the van Dam–Veltman–Zakharov (VDVZ) discontinuity. We present a solution for th...