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Fortuity in the D1-D5 system
by Chi-Ming Chang, Ying-Hsuan Lin, Haoyu Zhang
Submission summary
| Authors (as registered SciPost users): | Haoyu Zhang |
| Submission information | |
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| Preprint Link: | https://arxiv.org/abs/2501.05448v2 (pdf) |
| Date submitted: | Oct. 6, 2025, 8:17 p.m. |
| Submitted by: | Haoyu Zhang |
| Submitted to: | SciPost Physics |
| Ontological classification | |
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| Academic field: | Physics |
| Specialties: |
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| Approach: | Theoretical |
Abstract
We reformulate the lifting problem in the D1-D5 CFT as a supercharge cohomology problem, and enumerate BPS states according to the fortuitous/monotone classification. Focusing on the deformed $T^4$ symmetric orbifold theory, cohomology classes in the $N=2$ theory are explicitly constructed and matched with the exact BPS partition function. For general $N$, an infinite set of monotone cohomology classes are characterized and conjectured to be exhaustive. We further describe how to assemble BPS states at smaller $N$ into BPS states at larger $N$, and interpret their holographic duals as black hole bound states and massive stringy excitations on smooth horizonless (e.g. Lunin-Mathur) geometries.
Author indications on fulfilling journal expectations
- Provide a novel and synergetic link between different research areas.
- Open a new pathway in an existing or a new research direction, with clear potential for multi-pronged follow-up work
- Detail a groundbreaking theoretical/experimental/computational discovery
- Present a breakthrough on a previously-identified and long-standing research stumbling block
Current status:
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Strengths
- The lifting of supersymmetric states in the AdS3/CFT2 duality is reformulated in terms of a cohomology problem, and its solution is discussed for finite values of N.
- The article is well-written, and it has a nice balance between the original material and review of the literature. This makes the article self-contained.
Weaknesses
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The paper performs an impressive technical analysis, and the main results are briefly summarized at the end of the Introduction, but the article would benefit from a more detailed summary either in the discussion section (which is currently missing) or in the introduction. In particular, the current summary ends with the statement "it is natural to propose that the composite state is dual to a BPS stringy excitation on a smooth horizonless geometry corresponding to the cycle-length w2 monotone state.", but does not discuss the physical implications of this result. I recommend this article for publication once all original results are properly formulated and a discussion of their physical implications is added.
Requested changes
All original results should be explicitly formulated in the introduction or discussion sections, and a discussion of their physical implications should be added.
Recommendation
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