SciPost Submission Page
Split representation in celestial holography
by Chi-Ming Chang, Reiko Liu, Wen-Jie Ma
Submission summary
| Authors (as registered SciPost users): | Chi-Ming Chang · Wenjie Ma |
| Submission information | |
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| Preprint Link: | scipost_202312_00032v1 (pdf) |
| Date submitted: | Dec. 17, 2023, 9:41 a.m. |
| Submitted by: | Ma, Wenjie |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approach: | Theoretical |
Abstract
We develop a split representation for celestial amplitudes in celestial holography, by cutting internal lines of Feynman diagrams in Minkowski space. More explicitly, the bulk-to-bulk propagators associated with the internal lines are expressed as a product of two boundary-to-bulk propagators with a coinciding boundary point integrated over the celestial sphere. Applying this split representation, we compute the conformal partial wave and conformal block expansions of celestial four-point functions of massless scalars and photons on the Euclidean celestial sphere. In the $t$-channel massless scalar amplitude, we observe novel intermediate exchanges of staggered modules in the conformal block expansion.
Current status:
Reports on this Submission
Report #2 by Prahar Mitra (Referee 2) on 2024-5-3 (Invited Report)
Strengths
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The split representation of the AdS and dS propagators to obtain a new representation of celestial amplitudes in terms of lower point amplitudes (analogous to the conformal block expansion in a CFT)
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The result may help us learn more about the locality and unitarity properties of CCFTs and is, therefore, interesting.
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The presentation of the paper is clear and several examples are explored (with lengthy calculations).
Weaknesses
How can the split representation of the Feynman propagator be useful in this case?
Report
I recommend that it be published.
Requested changes
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Factors of $i\epsilon$ should be included in equations (4.2), (4.3), (4.4), (5.1) etc. to ensure that the relevant integrals are well-defined.
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There is an extra "[spin?]" in the first paragraph of section 5.2. Is that a typo?
Recommendation
Publish (easily meets expectations and criteria for this Journal; among top 50%)
Strengths
Weaknesses
Report
Requested changes
The statements about helicity vs spin at the beginning of section 5.2 are a little confusing. I'd recommend using helicity for the 4D quantities and spin for the 2D ones if everything is massless. I don't like the sentence that the shadow flips the helicity -- I think you just mean 2D spin, hence my comment above.