Antiscreening in perturbative quantum gravity and resolving the Newtonian singularity

TL;DR

This paper calculates quantum corrections to gravity, showing antiscreening of the Newtonian singularity and superluminal graviton propagation, supporting the asymptotic safety of quantum gravity.

Contribution

It provides a nonperturbative calculation of quantum effects on the Newtonian potential, demonstrating antiscreening and analyzing graviton propagation in quantum gravity.

Findings

Quantum effects antiscreen the Newtonian 1/r singularity.

Gravitons propagate superluminally due to quantum fluctuations.

Supports the asymptotic safety scenario in quantum gravity.

Abstract

We calculate the quantum corrections to the Newtonian potential induced by a massless, nonminimally coupled scalar field on Minkowski background. We make use of the graviton vacuum polarization calculated in our previous work and solve the equation of motion nonperturbatively. When written as the quantum-corrected gauge invariant Bardeen potentials, our results show that quantum effects generically antiscreen the Newtonian singularity 1/r. This result supports the point of view that gravity on (super-)Planckian scales is an asymptotically safe theory. In addition, we show that, in the presence of quantum fluctuations of a massless, (non)minimally coupled scalar field, dynamical gravitons propagate superluminally. The effect is, however, unbservably small and it is hence of academic interest only.