Seeking for resonances in unitarized one-loop graviton-graviton scattering

TL;DR

This paper applies the Inverse Amplitude Method to unitarize one-loop graviton-graviton scattering in pure gravity, investigating the existence of resonances like graviballs, and finds no evidence for such resonances.

Contribution

It introduces a novel application of unitarization techniques to quantum gravity scattering amplitudes, addressing infrared divergences and challenging recent claims of graviball resonances.

Findings

No evidence of graviball resonances was found.

Infrared divergences require careful treatment with regulators.

The method challenges previous studies suggesting graviballs.

Abstract

Some effective field theories exhibit dynamical resonances that, when properly included, mitigate their bad behaviour at high energies. Unitarization of the partial wave amplitudes is the preferred method to unveil such resonances. Interpreting the Einstein-Hilbert theory in the spirit of effective Lagrangians, we implement the Inverse Amplitude Method and unitarize the one-loop level graviton-graviton scattering in pure gravity. Due to the presence of infrared divergences, the analysis requires a careful treatment of the infrared region and the introduction of infrared regulators, carefully selected in order to fulfil perturbative unitarity. No evidence of any graviball is found, in contradiction with a recent study.