Gauge and Gravity Amplitudes on the Celestial Sphere

TL;DR

This paper explores the structure of gauge and gravity scattering amplitudes on the celestial sphere, demonstrating the persistence of double copy relations up to five particles using supersymmetric representations.

Contribution

It shows that double copy relations hold for celestial amplitudes up to five particles, extending known relations into the celestial sphere framework with supersymmetry.

Findings

Double copy relations hold for up to five particles on the celestial sphere.

Supersymmetric representations clarify the double copy structure.

Explicit factors modify the relations, identified through direct computation.

Abstract

The analytic structures of scattering amplitudes in gauge theory and gravity are examined on the celestial sphere. The celestial amplitudes in the two theories - computed by employing a regulated Mellin transform - can be compared at low multiplicity. It is established by direct computation that up to five external particles, the double copy relations of Kawai, Lewellen and Tye continue to hold identically, modulo certain multiplicative factors which are explicitly determined. Supersymmetric representations of the amplitudes are utilized throughout, manifesting the double copy structure between $\mathcal{N}=4$ super Yang-Mills and $\mathcal{N}=8$ supergravity on the celestial sphere.