One-loop four-graviton amplitudes in N=4 supergravity models

TL;DR

This paper computes one-loop four-graviton amplitudes in pure N=4 supergravity by deriving field theory limits from different string models, showing they yield identical results despite different origins.

Contribution

It provides a detailed comparison of amplitudes derived from various string models, confirming their equivalence in the pure supergravity limit.

Findings

All string-derived models produce the same four-graviton amplitude.

The contributions of spin-1 and spin-2 supermultiplets are explicitly extracted.

The results unify different string constructions in the supergravity limit.

Abstract

We evaluate in great detail one-loop four-graviton field theory amplitudes in pure N=4 D=4 supergravity. The expressions are obtained by taking the field theory limits of (4,0) and (2,2) space-time supersymmetric string theory models. For each model we extract the contributions of the spin-1 and spin-2 N=4 supermultiplets running in the loop. We show that all of those constructions lead to the same four-dimensional result for the four-graviton amplitudes in pure supergravity even though they come from different string theory models.