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Sailing past the End of the World and discovering the Island
by Tarek Anous, Marco Meineri, Pietro Pelliconi, Julian Sonner
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Submission summary
| Authors (as registered SciPost users): | Tarek Anous · Marco Meineri · Pietro Pelliconi · Julian Sonner |
| Submission information | |
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| Preprint Link: | https://arxiv.org/abs/2202.11718v3 (pdf) |
| Date submitted: | 2022-06-29 15:25 |
| Submitted by: | Pelliconi, Pietro |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approach: | Theoretical |
Abstract
Large black holes in anti-de Sitter space have positive specific heat and do not evaporate. In order to mimic the behavior of evaporating black holes, one may couple the system to an external bath. In this paper we explore a rich family of such models, namely ones obtained by coupling two holographic CFTs along a shared interface (ICFTs). We focus on the limit where the bulk solution is characterized by a thin brane separating the two individual duals. These systems may be interpreted in a double holographic way, where one integrates out the bath and ends up with a lower-dimensional gravitational braneworld dual to the interface degrees of freedom. Our setup has the advantage that all observables can be defined and calculated by only relying on standard rules of AdS/CFT. We exploit this to establish a number of general results, relying on a detailed analysis of the geodesics in the bulk. Firstly, we prove that the entropy of Hawking radiation in the braneworld is obtained by extremizing the generalized entropy, and moreover that at late times a so-called `island saddle' gives the dominant contribution. We also derive Takayanagi's prescription for calculating entanglement entropies in BCFTs as a limit of our ICFT results.
Current status:
Reports on this Submission
Report #1 by Anonymous (Referee 3) on 2022-7-8 (Invited Report)
- Cite as: Anonymous, Report on arXiv:2202.11718v3, delivered 2022-07-08, doi: 10.21468/SciPost.Report.5358
Strengths
1. Results are new and interesting.
2. Clearly written and coherently presented.
Weaknesses
I believe that the authors could have a better understanding of existing literature.
Report
This paper is interesting, it considers holographic interface conformal field theory (ICFT) and its reduction to holography boundary conformal field theory (BCFT). The model is described by braneworld and it is doubly holographic. The authors exploited the standard three equivalent descriptions of the braneworld holography to compute the correlators in the boundary description and look for its interpretation in the intermediate description regarding black holes. The calculation is done in the bulk description by geodesics approximation. There are two new perspectives from this paper. This first is that the geodesics computing the single sided ICFT correlator can go across the brane and come back and the second is that the island rule in the BCFT case can be derived from the ICFT case. This first perspective is interesting but in this paper the authors exclusively considered the AdS3 case where the geodesics are very simple and easy to cut and glue. It would be interesting to see whether the brane crossing and coming back geodesics exist in higher dimensional holographic ICFTs. The second perspective simply exploits the fact that the brane is gravitating and when we minimize the area of the bulk Ryu-Takayanagi surface we should also minimize over the possible end points of the bulk Ryu-Takayanagi surface on the brane. I recommend SciPost to accept this paper for publication.
Requested changes
I believe that the authors could have a better understanding of existing literature. Regarding this point, here are a few suggestions:
1. On top of Page 3: For BCFT models that can perform studies of black hole coupled to bath add https://inspirehep.net/literature/1751747, https://inspirehep.net/literature/1766462 and https://inspirehep.net/literature/1799453 to [9-12] and organize them chronologically. (The three equivalent descriptions are firstly emphasized in https://inspirehep.net/literature/1799453.)
2. Add https://inspirehep.net/literature/1766462 and https://inspirehep.net/literature/1799453 to [9,11] in “ Recent progress in understanding black-hole evaporation came from computing the same observables in either of the three descriptions”.
3. The relationship between BCFT entanglement entropy and island rule in braneworld holography is firstly refined in https://inspirehep.net/literature/1804322 and https://inspirehep.net/literature/1835408 (see equ (2.1)-(2.2)).