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Bulk locality from the celestial amplitude

by Chi-Ming Chang, Yu-tin Huang, Zi-Xun Huang, Wei Li

This Submission thread is now published as SciPost Phys. 12, 176 (2022)

Submission summary

As Contributors: Chi-Ming Chang
Arxiv Link: (pdf)
Date accepted: 2022-05-03
Date submitted: 2022-03-16 09:33
Submitted by: Chang, Chi-Ming
Submitted to: SciPost Physics
Academic field: Physics
  • High-Energy Physics - Theory
Approach: Theoretical


In this paper, we study the implications of bulk locality on the celestial amplitude. In the context of the four-point amplitude, the fact that the bulk S-matrix factorizes locally in poles of Mandelstam variables is reflected in the imaginary part of the celestial amplitude. In particular, on the real axis in the complex plane of the boost weight, the imaginary part of the celestial amplitude can be given as a positive expansion on the Poincar\'e partial waves, which are nothing but the projection of flat-space spinning polynomials onto the celestial sphere. Furthermore, we derive the celestial dispersion relation, which relates the imaginary part to the residue of the celestial amplitude for negative even integer boost weight. The latter is precisely the projection of low energy EFT coefficients onto the celestial sphere. We demonstrate these properties explicitly on the open and closed string celestial amplitudes. Finally, we give an explicit expansion of the Poincar\'e partial waves in terms of 2D conformal partial waves.

Published as SciPost Phys. 12, 176 (2022)

List of changes

Typo fixed. A reference added above (2.33). Clarification sentences added above (3.6), around (3.8) and below (5.5). Minor structure rearranged and sentences added in Section 3.1 and 6.

Reports on this Submission

Anonymous Report 1 on 2022-3-23 (Invited Report)


I am happy with all the changes and support the paper for publication in SciPost.

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