Unimodular Trees versus Einstein Trees

TL;DR

This paper calculates specific graviton scattering amplitudes in Unimodular Gravity and finds they match those in General Relativity, despite differences in their fundamental formulations.

Contribution

It demonstrates that MHV tree-level graviton amplitudes in Unimodular Gravity are identical to those in General Relativity, highlighting a surprising equivalence.

Findings

Amplitudes for 3, 4, 5 gravitons are computed.

Unimodular Gravity amplitudes match GR results.

Propagators and vertices differ between theories.

Abstract

The maximally helicity violating (MHV) tree level scattering amplitudes involving three, four or five gravitons are worked out in Unimodular Gravity. They are found to coincide with the corresponding amplitudes in General Relativity. This a remarkable result, insofar as both the propagators and the vertices are quite different in both theories.