Celestial double copy from the worldsheet

Understand

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.