N=8 Supergravity on the Light Cone

TL;DR

This paper develops a generating functional for light-cone superfield amplitudes in N=8 supergravity, providing insights into the structure of quantum corrections and supporting the conjecture of all-loop finiteness in four dimensions.

Contribution

It introduces a new functional approach to compute supergravity amplitudes and analyzes their non-locality and UV behavior, supporting all-loop finiteness.

Findings

Quantum corrections are non-local in transverse directions for fewer than a certain number of loops.

UV infinities are unlikely to appear before 7 loops in light-cone supergraph calculations.

The combination of E7 symmetry and recursion relations suggests all-loop finiteness of N=8 supergravity.

Abstract

We construct the generating functional for the light-cone superfield amplitudes in a chiral momentum superspace. It generates the n-point particle amplitudes which on shell are equivalent to the covariant ones. Based on the action depending on unconstrained light-cone chiral scalar superfield, this functional provides a regular d=4 QFT path integral derivation of the Nair-type amplitude constructions. By performing a Fourier transform into the light-cone chiral coordinate superspace we find that the quantum corrections to the superfield amplitudes with n legs are non-local in transverse directions for the diagrams with the number of loops smaller than n(n-1)/2 +1. This suggests the reason why UV infinities, which are proportional to local vertices, cannot appear at least before 7 loops in the light-cone supergraph computations. By combining the E7 symmetry with the supersymmetric recursion relations we argue that the light-cone supergraphs predict all loop finiteness of d=4 N=8 supergravity.