Unimodular trees versus Einstein trees

2016, September 15
Enrique Álvarez, Sergio González-Martín, Carmelo P. Martín
The European Physical Journal C
  art_10.1140_epjc_s10052-016-4384-2.pdf

The maximally helicity violating 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 the two theories.