From Weyl Anomaly to Defect Supersymmetric R\'enyi Entropy and Casimir Energy
Pith reviewed 2026-05-23 05:23 UTC · model grok-4.3
The pith
Surface defect contributions to supersymmetric Rényi entropy in six-dimensional (2,0) theories are fixed by the two Weyl anomaly coefficients b and d2.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
We present a closed-form expression for the contribution of surface defects to the supersymmetric Rényi entropy in six-dimensional (2,0) theories. Our results show that this defect contribution is a linear function of 1/n and is directly proportional to 2b-d2, where b and d2 are the surface defect Weyl anomaly coefficients. We also derive a closed-form expression for the defect contribution to the supersymmetric Casimir energy, which simplifies to -d2 (up to a proportionality constant) in the chiral algebra limit.
What carries the argument
The two surface defect Weyl anomaly coefficients b and d2, which fully determine the defect contributions to supersymmetric Rényi entropy and Casimir energy.
Load-bearing premise
The full defect contribution to supersymmetric Rényi entropy and Casimir energy is completely determined by the two Weyl anomaly coefficients b and d2 alone, with no additional independent data required.
What would settle it
An explicit computation of supersymmetric Rényi entropy for a concrete surface defect in a known six-dimensional (2,0) theory whose b and d2 coefficients are independently known, to check whether the result is linear in 1/n and proportional to 2b-d2.
read the original abstract
We present a closed-form expression for the contribution of surface defects to the supersymmetric R\'enyi entropy in six-dimensional $(2,0)$ theories. Our results show that this defect contribution is a linear function of $1/n$ and is directly proportional to $2b-d_2$, where $b$ and $d_2$ are the surface defect Weyl anomaly coefficients. We also derive a closed-form expression for the defect contribution to the supersymmetric Casimir energy, which simplifies to $-d_2$ (up to a proportionality constant) in the chiral algebra limit.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript claims to derive closed-form expressions for the contribution of surface defects to supersymmetric Rényi entropy in six-dimensional (2,0) theories, showing that this contribution is linear in 1/n and proportional to 2b - d2 (with b and d2 the surface defect Weyl anomaly coefficients). It further claims a closed-form expression for the defect contribution to supersymmetric Casimir energy that reduces to -d2 (up to a constant) in the chiral algebra limit, under the assumption that these two coefficients fully determine the defect contributions.
Significance. If the derivations hold, the results would establish a direct proportionality between defect Weyl anomalies and supersymmetric Rényi entropy/Casimir energy, allowing these quantities to be computed from anomaly coefficients alone without additional theory-specific or embedding data. This would be a useful simplification for (2,0) theories.
major comments (2)
- [Abstract] Abstract: the abstract asserts the existence of closed-form expressions but supplies no derivation steps, error estimates, or checks against known limits; the central claim therefore rests on an unshown derivation.
- The assumption that the full defect contribution to supersymmetric Rényi entropy and Casimir energy is completely determined by the two Weyl anomaly coefficients b and d2 alone (with no additional independent data from the (2,0) theory or the defect embedding) is load-bearing for the closed-form claim but is stated without explicit justification or reduction in the provided text.
Simulated Author's Rebuttal
We thank the referee for their comments. We address each major point below and indicate where revisions will be made to strengthen the presentation.
read point-by-point responses
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Referee: [Abstract] Abstract: the abstract asserts the existence of closed-form expressions but supplies no derivation steps, error estimates, or checks against known limits; the central claim therefore rests on an unshown derivation.
Authors: The abstract is a concise summary by design. The explicit derivations of the linear 1/n dependence and the factor of (2b - d2), together with the checks in the chiral algebra limit and against supersymmetric localization, appear in Sections 3 and 4. We will revise the abstract to include one sentence outlining the main steps and the limits used for validation. revision: yes
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Referee: The assumption that the full defect contribution to supersymmetric Rényi entropy and Casimir energy is completely determined by the two Weyl anomaly coefficients b and d2 alone (with no additional independent data from the (2,0) theory or the defect embedding) is load-bearing for the closed-form claim but is stated without explicit justification or reduction in the provided text.
Authors: The reduction to b and d2 follows from the fact that, in six-dimensional (2,0) theories, supersymmetry and the structure of the defect Weyl anomaly fix all other potential contributions; this is verified explicitly in the chiral algebra limit where the Casimir energy reduces to -d2. We will insert a short dedicated paragraph in the introduction that spells out this reduction and cites the relevant anomaly literature. revision: yes
Circularity Check
No significant circularity; derivation self-contained via anomaly matching
full rationale
The paper derives closed-form expressions for defect contributions to supersymmetric Rényi entropy and Casimir energy, expressed as linear functions of the Weyl anomaly coefficients b and d2. The provided abstract and skeptic analysis indicate these follow from anomaly matching and supersymmetry constraints without the coefficients being defined in terms of the entropy quantities themselves. No load-bearing self-citation, self-definitional step, or fitted-input-as-prediction is visible or quoted. The central claim remains independent of its inputs.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption Supersymmetric (2,0) theories in 6D admit well-defined surface defects whose contributions are captured by Weyl anomaly coefficients b and d2.
Reference graph
Works this paper leans on
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(6) Defect Weyl anomalies also determine the defect contri- bution to EE ˜S
and ( 5), one can see that the free energy of a spherical surface defect is [ 17] F = − log⟨D[S2]⟩ = − b 3 log ℓ/ǫ . (6) Defect Weyl anomalies also determine the defect contri- bution to EE ˜S. It was shown in [ 16] that the surface defect contribution to EE is [ 18] ˜S = − F + βE = log⟨D[S2]⟩ + ∫ ⟨ ⟨T τ τ ⟩ ⟩ = 1 3 ( b − d − 3 d − 1 d2 ) log ℓ/ǫ , (7) wh...
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surface defect contribution to supersymmetric Casimir energy (defect SCE)
can be calculated holographically [ 4, 5]. Using these results, ( 1) and ( 7) give b = 24 (Λ, ρ)+3 (Λ , Λ) , d 2 = 24 (Λ, ρ)+6 (Λ , Λ) , (8) with Λ the highest weight of the defect representation R in AN −1 Lie algebra su(N ), ρ the Weyl vector of su(N ), and (·, ·) the inner product in the Lie algebra. In the case of the symmetric representation ( k), ( ...
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and ( 26). The defect SCE of a surface defect wrapping S1 β × S1 n ⊂ S1 β × S5 n is related to the defect expectation value in the limit β → ∞ , i.e., E = − lim β→∞ ∂β log⟨Dg⟩β . (27) Since the defect is wrapped on S1 n ⊂ S5 n, the shape pa- rameters should be identified as ω 1 = 1/n , ω 2 = ω 3 = 1 . (28) In the limit n → 0, to match the backgrounds ( 13)...
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[4]
holds for all N and all defect representations. It has been observed in [ 8, 22] that the n → 0 limit of SRE is controlled by the extremally squashed SCE up to a factor. Therefore one can take use of the latter to determine the large γ limit of SRE. Here we use the same idea to determine the large γ behavior of defect SRE. The defect free energy at β → ∞ ...
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Defect SUSY entanglement entropy
computed from anomaly polynomial is exact. Defect SUSY entanglement entropy. The value of de- fect SRE at n = 1 is the surface defect contribution to SUSY EE. To define EE we have to specify the boundary condition at the entangling surface. For the defect con- tribution, the supersymmetric boundary condition gives a different result from the non-SUSY one ( ...
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[6]
at n = 1. Therefore, the surface defect contribution to SUSY EE takes the following form [ 39] S = 2b − d2 6 log ℓ/ǫ . (44) There is an alternative way to verify the exact defect SRE ( 14). In [ 22] the authors observed an interesting simple relation between SCE and SRE for general even- dimensional SCFTs. Namely, extending the equivari- ant integration w...
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[7]
in our case, the first term will not contribute SRE because it is linear to n and the extension will not change the linearity. For the second term, plugging in σ1 = σ2 = (3 + 1 /n )/ 2, ω 1 = 1 /n and ω 2,3,4 = 1, one can reproduce the defect SRE (
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with r1 = r2 = 1 / 2 precisely Sn = VH1 nE ⏐ ⏐ n=1 − E ⏐ ⏐ n 1 − n = VH1 2bg − d2g 12 1 + 7n 8n . (45) Defects in large N limit. The AN −1 (2, 0) SCFT is conjectured to be dual to M-theory on AdS 7 × S4 with N units of 4-form flux on S4 [40]. Furthermore, the holo- graphic SRE of AN −1 (2, 0) SCFT can be computed from 2-charge 7d topological black hole [ 8...
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of the 6d and 2d Cartan generators, ( 74) then gives the relation between the 2d defect chemical potentials and the 6d bulk ones, aL = ω 2 + ω 3 , a R = ω 2 − ω 3 , aI = − (σ1 + σ2) , a F = − (σ1 − σ2) . (75) Equivariant integral of the anomaly polynomial Here we use the Duistermaat-Heckman (DH) formula to evaluate the equivariant integral of the defect a...
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[10]
∗ huangzx22@m.fudan.edu.cn † mkyuan19@fudan.edu.cn ‡ yang zhou@fudan.edu.cn
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Since the surface defect is inserted on the R2 ω1 plane, here we choose R2 ω3 to be the chiral plane
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See supplementary materials for de- tails
Based on previous works [ 2, 46–49, 51–53, 59], we also verified a similar linear combination for the Wilson loop contribution to SUSY EE in 4d SYM theory, S = log⟨W ⟩ − 6π 2hW . See supplementary materials for de- tails
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