On-shell Techniques and Universal Results in Quantum Gravity

TL;DR

This paper uses modern on-shell techniques to compute universal quantum and post-Newtonian corrections to Coulomb and Newtonian potentials, simplifying previous methods and analyzing spin effects.

Contribution

It introduces a streamlined on-shell approach employing spinor-helicity variables, KLT relations, and unitarity methods to derive universal corrections in quantum gravity.

Findings

Verified previous correction results with a simpler method

Demonstrated universality of corrections across theories

Analyzed spin dependence of the corrections

Abstract

We compute the leading post-Newtonian and quantum corrections to the Coulomb and Newtonian potentials using the full modern arsenal of on-shell techniques; we employ spinor-helicity variables everywhere, use the Kawai-Lewellen-Tye (KLT) relations to derive gravity amplitudes from gauge theory and use unitarity methods to extract the terms needed at one-loop order. We stress that our results are universal and thus will hold in any quantum theory of gravity with the same low-energy degrees of freedom as we are considering. Previous results for the corrections to the same potentials, derived historically using Feynman graphs, are verified explicitly, but our approach presents a huge simplification, since starting points for the computations are compact and tedious index contractions and various complicated integral reductions are eliminated from the onset, streamlining the derivations. We also analyze the spin dependence of the results using the KLT factorization, and show how the spinless correction in the framework are easily seen to be independent of the interacting matter considered.