SciPost Submission Page
Asymptotic T-duality in three dimensions
by Stéphane Detournay, José Figueroa, Alejandro Vilar López
Submission summary
| Authors (as registered SciPost users): | Alejandro Vilar López |
| Submission information | |
|---|---|
| Preprint Link: | scipost_202504_00021v2 (pdf) |
| Date accepted: | July 15, 2025 |
| Date submitted: | July 6, 2025, 10:19 p.m. |
| Submitted by: | Alejandro Vilar López |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approach: | Theoretical |
Abstract
In (super)gravity theories, T-duality relates solutions with an exact isometry which can have wildly different asymptotic behaviors: a well-known example is the duality between BTZ black holes and (non-extremal) three-dimensional black strings. Using this dual pair, we show how the knowledge of a phase space which includes one set of solutions (here, BTZ black holes embedded in the Brown-Henneaux phase space) allows to obtain a phase space for the dual set via an asymptotic notion of T-duality. The resulting asymptotic symmetry algebras can be very different. For our particular example, we find a large algebra of symmetries for the black string phase space which includes as subalgebras $\mathfrak{bms}_2$, $\mathfrak{bms}_3$, and a twisted warped conformal algebra. On the way, we show that a chiral half of the Brown-Henneaux boundary conditions are dual to the Compère-Song-Strominger ones.
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
Author comments upon resubmission
List of changes
- New references have been added at the beginning of the second paragraph of the introduction to justify the pivotal role played by the BTZ black hole in developing different aspects of AdS/CFT.
- Around equation (1), both before and after, we have added a more detailed description of what the dynamical fields are and what this theory describes (it is the "low energy string effective theory governing the NS-NS sector").
- We have explicitly stated below equation (29) that the algebra has the structure of a semi-direct product.
- We have explicitly stated in the paragraph above (34) that one can directly check from Buscher rules that gauge transformations of the B-field become diffeomorphisms after T-duality.
- We have added figure 1 (page 16) to help understanding how the sign of A(z,w) affects the asymptotic form of the Cauchy slices.
- We have added footnote 12 in page 16 mentioning the recent work on kinematical charges and the interesting possibility that some of the charges we find are of that kind.
- We have corrected a typo in the last sentence of the paragraph below (62). It said "For R, ..." when it should be "For T, ...".
- We have added two sentences to the first paragraph of the discussion, with the aim to clarify that the construction described in the paper does not directly relate phase spaces, but rather it provides new boundary conditions from existing ones (the analysis of the new phase space has to be done subsequently from scratch).
- We have added footnote 14 (page 18) to remark that the construction can be done without significant change in any dimension, even though we illustrated it with a three-dimensional example.
Published as SciPost Phys. 19, 044 (2025)
Reports on this Submission
Report #1 by Luca Ciambelli (Referee 2) on 2025-7-8 (Invited Report)
- Cite as: Luca Ciambelli, Report on arXiv:scipost_202504_00021v2, delivered 2025-07-08, doi: 10.21468/SciPost.Report.11525
Report
The authors addressed my concerns and improved the readability and soundness of the paper. I am glad to recommend this paper for submission in JHEP.
I do not need to revise this manuscript further, but I'd like to point out that my point 3 in the previous report, regarding the semantic of falloffs vs boundary conditions, could be addressed better by the authors. Indeed, the way the authors replied and the discussion around equations 5a-5c can truly lead to confusion. Allow me to explain by providing two different and mutually inconsistent ways of reading these equations as they stand:
1) I might interpret that only the leading term in each expansion is held fixed on the phase space, such that $\delta \eta_{ab}=0$ and $\delta C_0=0$, and the subleading terms are dynamical phase space variable.
2) Conversely, I might interpret these equations as stating that all terms displayed are phase space constants, while the subleading terms not displayed are dynamical: $\delta \eta_{ab}=0=\delta Y_{ab}$, $\delta C_0=0, \delta b=0, \delta \beta=0$, and $\delta \tilde Y=0=\delta \phi$. Note that this is the approach of the original Brown-Henneaux and Strominger papers, which differs from the most recent implicit approach, based more on interpretation 1).
Obviously 1) and 2) are very different phase spaces and, while I perfectly agree with the authors that it is common jargon to confuse falloffs and boundary conditions, it would be better to avoid doing so, in order to make sure that the setup is clear and unambiguously defined.
As I said, this is merely a suggestion aimed at making the manuscript more precise and rigorous, it does not affect the correctness of the paper and its suitability for publication.
Recommendation
Publish (easily meets expectations and criteria for this Journal; among top 50%)
Author: Alejandro Vilar López on 2025-07-15 [id 5644]
(in reply to Report 1 by Luca Ciambelli on 2025-07-08)We thank the referee again for his constructive comments: indeed, we had not realized that as writtten equation (5) could lead to confusions due to some terms being kept fixed while others being dynamical phase space variables. We will add a footnote in a new version to clarify this.