Unitarized one-loop graviton-graviton scattering

TL;DR

This paper applies the Inverse Amplitude Method to unitarize one-loop graviton-graviton scattering amplitudes, extending the validity of perturbative results to near the Planck scale and exploring potential dynamical resonances.

Contribution

It introduces a unitarization approach to one-loop graviton scattering, revealing possible resonances and extending the energy range of perturbative quantum gravity calculations.

Findings

Extended the applicability of perturbative graviton scattering to higher energies.

Identified potential dynamical resonances in specific helicity channels.

Demonstrated the effectiveness of the Inverse Amplitude Method in quantum gravity context.

Abstract

In this work we interpret the Einstein-Hilbert (EH) Lagrangian of gravitation as the first term of a low-energy effective theory similar to those considered in the chiral Lagrangian approach to low-energy hadron physics or the electroweak chiral Lagragians describing the symmetry breaking sector of the Standard Model (SM). Starting from the one-loop computation of the elastic graviton-graviton scattering amplitude by Dunbar and Norridge, we unitarize the IR regularized partial waves by using the Inverse Amplitude Method (IAM). This method enlarges the regime of applicability of the perturbative results to higher energies of the order of the Plank scale $M_P$ and allows for the possibility of poles in the second Riemann which have the natural interpretation of dynamical resonances. In this work we look for these possible resonances for the $++++$ and $ -- -$ helicity channels and the $J=0$, $2$ and $4$ partial waves.