Celestial double copy from the worldsheet

TL;DR

This paper derives compact formulas for tree-level celestial amplitudes across various theories using ambitwistor string theory, extending the celestial double copy and elucidating color-kinematics duality in this context.

Contribution

It introduces a novel framework for computing celestial amplitudes with all multiplicities and extends the celestial double copy to arbitrary external states.

Findings

Derived compact CHY-like formulas for celestial amplitudes

Extended the celestial double copy to all multiplicities

Connected color-kinematics duality to generalized twisted cohomology

Abstract

Using the ambitwistor string, we compute tree-level celestial amplitudes for biadjoint scalars, Yang-Mills and gravity to all multiplicities. They are presented in compact CHY-like formulas with operator-valued scattering equations and numerators acting on a generalized hypergeometric function. With these we extend the celestial double copy to tree-level amplitudes with arbitrary number of external states. We also show how color-kinematics duality is implemented in celestial amplitudes and its interpretation in terms of a generalized twisted cohomology theory.