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Euclidean Wormholes and Gravitational States
by Alexandre Belin
Submission summary
| Authors (as registered SciPost users): | Alexandre Belin |
| Submission information | |
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| Preprint Link: | https://arxiv.org/abs/2508.14165v2 (pdf) |
| Date submitted: | Nov. 18, 2025, 9:34 a.m. |
| Submitted by: | Alexandre Belin |
| Submitted to: | SciPost Physics |
| Ontological classification | |
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| Academic field: | Physics |
| Specialties: |
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| Approach: | Theoretical |
Abstract
Euclidean wormholes are known to encode important non-perturbative effects in the physics of quantum black holes. In this paper, we discuss the slicing of Euclidean wormholes along a time-reflection symmetric slice which treats half of the Euclidean geometry as a gravitational machinery to produce a semi-classical state. This type of state preparation is different from Hartle-Hawking states prepared with the CFT path integral, such as the thermofield-double state. Nevertheless, the two different types of states have order one overlaps provided the gravitational data agrees on the initial data slice. This raises an interesting puzzle: one can easily construct an infinite family of semi-classical states that have order one overlap with the thermofield double state, while having a very different Euclidean preparation. We provide a microscopic description of wormhole states in the dual CFT and reformulate the factorization puzzle in the language of entanglement and the Hilbert space.
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
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Overall, the article is well written and contains new insights. My main question concerns eqn. (4.10), where the author claims that the moduli of the relevant partition functions can are tuned so that the overlap between the TFD state and the wormhole state is approximately one. Could the author provide additional explanation for how this is shown exactly? As currently written, the statement reads more like an expectation from the gravity picture than an independent field-theory argument.
I also have two minor comments:
1) In Eq. (3.3), is the intended relation “x ~ x + x_0”?
2) It seems similar phenomenon also appears in even lower-dimensional examples, such as the Maldacena-Qi model of two coupled SYK models. There, the ground state of the model also has overlap one with the TFD state at the classical level.
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