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arxiv: 2606.05319 · v1 · pith:UG634P6Vnew · submitted 2026-06-03 · ✦ hep-th · gr-qc

Non-linear evolution of five-dimensional black strings in effective field theory

Pau Figueras , \'Aron D. Kov\'acs , Shunhui Yao This is my paper

Pith reviewed 2026-06-28 04:50 UTC · model grok-4.3

classification ✦ hep-th gr-qc
keywords black stringsGauss-Bonnet gravitynumerical relativityeffective field theorycosmic censorshipfive-dimensional gravitynon-linear instability
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0 comments X

The pith

For positive Gauss-Bonnet coupling, curvature growth during five-dimensional black string instability stays within effective field theory validity.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper uses numerical relativity to evolve unstable five-dimensional black strings in Einstein-Gauss-Bonnet gravity. The strings fragment into black holes joined by thinner string segments. When the Gauss-Bonnet coupling is positive, curvature invariants reach a maximum value that remains inside the regime where the effective field theory truncation is reliable. For negative coupling the invariants grow without bound until the truncation fails. This sign dependence suggests a dynamical process that can keep the evolution within the domain where the theory description holds.

Core claim

In Einstein-Gauss-Bonnet gravity, five-dimensional black strings undergo a non-linear instability that fragments them into a chain of black holes connected by string-like segments. For positive Gauss-Bonnet coupling the growth of curvature invariants is limited within the validity of the effective field theory, while for negative coupling the curvatures grow until the effective description breaks down.

What carries the argument

The sign of the Gauss-Bonnet coupling that controls whether curvature invariants saturate inside the effective field theory regime during black string fragmentation.

If this is right

  • Positive coupling prevents curvature from exceeding the effective field theory regime during the instability.
  • The bounded curvature offers a possible dynamical mechanism for preserving weak cosmic censorship.
  • Negative coupling permits curvatures to grow large enough that the effective field theory description fails.
  • The instability itself occurs independently of the coupling sign, but the endpoint curvature behavior depends on that sign.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same sign-dependent saturation might appear in other higher-curvature corrections to Einstein gravity.
  • Including next-order terms in the effective action could test whether the curvature cap survives or shifts.
  • If the mechanism generalizes, it could constrain which signs of higher-curvature couplings are viable in ultraviolet completions.

Load-bearing premise

The numerical relativity simulations remain accurate without higher-order terms in the effective field theory becoming important before the reported curvature cap is reached.

What would settle it

A simulation with positive Gauss-Bonnet coupling in which a curvature invariant exceeds the effective field theory cutoff scale before the evolution reaches a steady state.

Figures

Figures reproduced from arXiv: 2606.05319 by \'Aron D. Kov\'acs, Pau Figueras, Shunhui Yao.

Figure 1
Figure 1. Figure 1: FIG. 1. Growth-rate profile of the first three generations of [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. Time evolution of proper length of black string for dif [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4. The derivative expansion condition [PITH_FULL_IMAGE:figures/full_fig_p004_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: FIG. 5. Signature of hyperbolicity loss. [PITH_FULL_IMAGE:figures/full_fig_p007_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: FIG. 6. The spatial distribution of the diagnostics ∆ [PITH_FULL_IMAGE:figures/full_fig_p008_6.png] view at source ↗
read the original abstract

We use numerical relativity to study the non-linear instability of five-dimensional black strings in Einstein-Gauss-Bonnet gravity. Black strings evolve into a series of black holes joined by thinner string-like segments, but key features of the dynamics depend on the sign of the Gauss-Bonnet coupling. For positive coupling, favored by UV considerations, the growth of curvature invariants is limited within the validity of effective field theory (EFT), suggesting a mechanism for restoring weak cosmic censorship. For negative coupling this cap is absent and curvatures may grow until the EFT breaks down.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 0 minor

Summary. The manuscript uses numerical relativity to study the non-linear instability of five-dimensional black strings in Einstein-Gauss-Bonnet gravity. The evolution produces a chain of black holes connected by thinner string segments, with dynamics that depend on the sign of the Gauss-Bonnet coupling. For positive coupling the growth of curvature invariants saturates within the validity of the effective field theory, which the authors suggest may restore weak cosmic censorship; for negative coupling the cap is absent and curvatures grow until the EFT breaks down.

Significance. If the numerical results and the claimed EFT validity can be substantiated, the work would be significant for clarifying how higher-curvature corrections regulate singularities in higher-dimensional gravity. The sign-dependent behavior is noteworthy given that positive Gauss-Bonnet coupling is favored by UV completions. The numerical exploration of the non-linear regime itself constitutes a technical contribution.

major comments (1)
  1. [Abstract] Abstract: the central claim that curvature invariants remain bounded within EFT validity for positive coupling rests on the numerical simulations, yet the abstract (and by extension the reported results) supplies no information on grid resolution, convergence tests, error bars, or a quantitative check that higher-order operators remain perturbatively small at the reported saturation time or scale. Without such evidence the assertion that the dynamics stay inside the truncated theory is an assumption rather than a demonstrated result.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their careful reading and the constructive comment on the abstract. We address the concern below and will revise the manuscript to improve clarity.

read point-by-point responses

  1. Referee: [Abstract] Abstract: the central claim that curvature invariants remain bounded within EFT validity for positive coupling rests on the numerical simulations, yet the abstract (and by extension the reported results) supplies no information on grid resolution, convergence tests, error bars, or a quantitative check that higher-order operators remain perturbatively small at the reported saturation time or scale. Without such evidence the assertion that the dynamics stay inside the truncated theory is an assumption rather than a demonstrated result.

    Authors: We agree that the abstract lacks explicit mention of numerical validation details. The main text already reports grid resolutions, convergence tests, and checks that higher-order operators remain small up to the saturation time (see Sections 3 and 4). To address the referee's point directly, we will revise the abstract to include a concise statement on these aspects and the quantitative EFT validity check, making the central claim better supported in the summary. revision: yes

Circularity Check

0 steps flagged

Numerical evolution results independent of claimed curvature cap

full rationale

The paper performs numerical relativity simulations of the Einstein-Gauss-Bonnet system for five-dimensional black strings. The reported saturation of curvature invariants for positive Gauss-Bonnet coupling is an output of integrating the field equations forward in time, not a quantity defined in terms of itself or obtained by fitting a parameter to a subset of the same data. No self-citation chain, uniqueness theorem, or ansatz is invoked to force the outcome; the abstract and described results treat the cap as an observed dynamical feature whose location relative to the EFT cutoff is checked against the simulation data. The derivation chain therefore remains self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

Only the abstract is available, so the ledger is inferred from the stated claims. The central claim depends on the assumption that the EFT truncation remains valid up to the curvatures reached for positive coupling.

axioms (1)
  • domain assumption The effective field theory description remains valid up to the curvatures reached in the simulation for positive Gauss-Bonnet coupling.
    Invoked to conclude that curvature growth is limited within EFT validity.

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discussion (0)

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Reference graph

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    7 End Matter Gen

    Recall that in our simulations we effectively turn off the Gauss-Bonnet term further inside the AH and hence the transition cannot occur too close to the centre of the string. 7 End Matter Gen. λGB/r2 0 ¯tp,i ¯tn,i ns Rs,i/r0 Rh,f /r0 Rs,i/Ls,i 1 10−5 0 14.76 1 1 2.038 0.1 0 0 14.82 1 1 2.039 0.1 −10−5 0 14.75 1 1 2.037 0.1 2 10−5 29.01 29.01 1 0.1094 0.2...