SciPost Submission Page
Revisiting Recent Progress in the Karch-Randall Braneworld
by Hao Geng
Submission summary
| Authors (as registered SciPost users): | Hao Geng |
| Submission information | |
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| Preprint Link: | https://arxiv.org/abs/2306.15671v4 (pdf) |
| Date submitted: | May 19, 2025, 4:35 a.m. |
| Submitted by: | Geng, Hao |
| Submitted to: | SciPost Physics |
| Ontological classification | |
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| Academic field: | Physics |
| Specialties: |
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| Approach: | Theoretical |
Abstract
Motivated by the study of entanglement island in the Karch-Randall braneworld, it has been conjectured and proven in general that entanglement island is not consistent with long-range (massless) gravity. In this paper, we provide a careful check of this conclusion in a model of massless gravity that is constructed using the Karch-Randall braneworld. We show that there is indeed no entanglement island and hence not a nontrivial Page curve due to the diffeomorphism invariance if we are studying the correct question which is though subtle. Moreover, we show that this conclusion is not affected by deforming the setup with the Dvali--Gabadadze--Porrati (DGP) terms. Furthermore, we show that the consistency of holography in this model will provide nontrivial constraints to the DGP parameters. This study provides an example that causality and holography in anti-de Sitter space can be used to constrain low energy effective theories. At the end, we clarify several subtleties in the braneworld gravity which are overlooked in the literature and we discuss the robustness of the above results against possible coarse-graining protocols to define a subregion in a gravitational theory.
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
The paper start with demonstrating why the claim of the existence of island in a massless gravity constructed out of the KR braneworld is wrong but an explicit and straightforward calculation using the RT formula.
The swampland criterion proposed in this paper has been explored in a follow-up paper in SciPost Phys. 15 (2023) 5, 199.
An explicit demonstrating calculation resolving the causality puzzle in KR braneworld is added in Section 4.2.
List of changes
Added Section 4.4 as asked by the referee 2.
Added a new Section 4.2 with an explicit calculation demonstrating the resolution of the causality puzzle in KR braneworld.