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.
Highlights
While an all-multiplicity proof could be found using the methods employed in [17], which relied on position space Feynman rules, they soon become cumbersome
We show how colorkinematics duality is implemented in celestial amplitudes and its interpretation in terms of a generalized twisted cohomology theory
Using the formulas computed using the ambitwistor string for celestial amplitudes we show that tree-level celestial Yang-Mills and gravity amplitudes are related by a double copy, generalizing the procedure given for low points in [17]
Summary
In order to make this paper self-contained we quickly review some background on recent technology used in the study of amplitudes. We keep the reviews short and focused on what is needed in the rest of the paper. In subsection 2.1 we review some facts about celestial amplitudes, in subsection 2.2 CHY formulas and the scattering equations are introduced. In subsection 2.3 we recall the basics of color-kinematics duality, and in subsection 2.4 we review how the CHY formulas and double copy are to be interpreted in light of twisted cohomology on the moduli space of punctured Riemann spheres
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