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The Non-BPS Black Hole Attractor Equation

High Energy Physics - Theory · Submitted 31 Jan 2006 · 26 references

Pith's verdict: A clean rewriting of the non-BPS extremum condition plus one genuinely new double-extremal solution, but the 'equivalent to minimizing V_BH' claim is asserted rather than proved and the Section 5 checks are consistency checks of the algebra.

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arXiv IDhep-th/0602005 (version 2)
Pith ID47OJCRUA, Pith's permanent record of this paper and its review
CitationMasoud Soroush, Navin Sivanandam, Renata Kallosh. "The Non-BPS Black Hole Attractor Equation." arXiv:hep-th/0602005 (2006). https://pith.science/paper/47OJCRUA
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The paper

The paper claims

The paper derives a single algebraic equation that fixes the shape moduli of a non-supersymmetric extremal black hole at its horizon, and argues that only zero-temperature black holes can do this at all.

The reading

A black hole made of charged fluxes in a Calabi–Yau compactification drags the surrounding shape moduli of the internal space to fixed values at its horizon, whatever those moduli were far away. For supersymmetric black holes this attractor behaviour is classical and well understood; the question here is whether it survives when supersymmetry is broken. The authors argue physically that what matters is not supersymmetry but extremality: an extremal black hole has an infinite throat, so the proper distance to the horizon is infinite, and a scalar rolling down the black hole potential has unlimited 'time' to settle at the critical point. A non-extremal black hole has a finite distance to its horizon, so the scalar arrives with its initial conditions still imprinted. They then derive an explicit attractor equation, $h = 2Im[ZΠ - (D̄_aD̄_bZ)G^{ac}G^{bd}D_cZ D_dΠ/(2Z)]$, whose solutions are supposed to be exactly the horizon values of the moduli, and check it against three worked examples.

What carries the argument

The load-bearing object is the Hodge decomposition of the three-form flux threading the Calabi–Yau, $H_3 = 2Im[ZΩ_3 + D̄_aZ G^{āa}D_aΩ_3]$, which is valid at any point of moduli space and therefore carries no information about the horizon by itself. The dynamical input comes from the extremum condition $2(D_aZ)Z̄ + iC_{abc}G^{bd}G^{ce}D̄_dZ̄ D̄_eZ̄ = 0$, which lets the authors replace $D_aZ$ by a quadratic expression in $D̄Z̄$ and substitute back into the decomposition. A special-geometry identity, $D_aD_bΩ = iC_{abc}G^{c d̄}D̄_{d̄}Ω$, removes the second derivatives of $Ω$ from the expansion so that only $Ω$, $DΩ$ and $D̄Ω$ appear. The resulting equation is algebraic in the charges and the moduli, so the horizon values can be read off without solving any flow.

Extended reading notes

Core claim

The central claim is that the non-supersymmetric attractor equation (4.12) holds in $N=2$ special geometry for BPS and non-BPS extremal black holes alike, and that solving it in terms of the electric and magnetic charges is equivalent to extremizing the black hole potential $V_{BH}=|Z|^2+|DZ|^2$. For BPS solutions the second term vanishes because $D_cZ=0$ and the equation collapses to the familiar $h=2Im[ZΠ]$; for non-BPS solutions the two terms must conspire so that the moduli become functions of the charges. The authors verify this in a large-volume Calabi–Yau with only D0 and D4 charges, where both the supersymmetric branch $t^2=q_0/D$ and the non-supersymmetric branch $t^2=-q_0/D$ fall out of a single algebraic condition $(Y-4)(Y-2)=0$; in a double-extremal non-BPS solution obtained by flipping the sign of $q_0$; and in the mirror quintic near the Gepner point, where the ratio $n_1/n_2$ solves a quadratic with roots $0.381$ (supersymmetric) and $-0.319$ (non-supersymmetric).

Load-bearing premise

The equation is obtained by feeding the condition that the black hole potential has a critical point into a flux decomposition that the authors themselves note holds everywhere in moduli space, so the equation's entire content is the potential-minimization picture, and the agreement with minimizing that potential in the examples is guaranteed rather than independent.

Editorial extensions

If this is right

  • Horizon moduli of non-BPS extremal black holes are computable from charge data alone, by solving one algebraic equation rather than an ordinary differential equation along the radial flow.
  • The same charge vector can admit both a supersymmetric and a non-supersymmetric attractor, so which one is realized is a separate dynamical question rather than a consequence of the charges.
  • Double-extremal non-BPS black holes exist and are obtained from their BPS counterparts by continuing the electric charge $q_0 \to -q_0$, with Reissner–Nordström geometry and constant scalars everywhere.
  • Because the non-BPS vacuum has no supersymmetric minimum to decay into, and because the black hole is at zero temperature, such configurations are stable against both decay and evaporation.
  • Attractor behaviour is tied to extremality rather than to unbroken supersymmetry, which reframes the mechanism as a statement about near-horizon geometry.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • The infinite-throat argument suggests a sharp diagnostic in other settings: any horizon with a finite proper distance should show scalars that remember their asymptotic values, which is in principle checkable numerically by shooting from several initial conditions.
  • Since the attractor equation is algebraic in the charges, it can be read as a map from a charge vector to a point in moduli space, and one could ask about the image of that map — which moduli values are reachable by some choice of fluxes.
  • The paper's analogy with the O'Raifeartaigh model suggests looking for string compactifications whose effective superpotential admits no supersymmetric critical point at all, which would make the non-supersymmetric vacuum stable by the same logic.
  • The authors flag in the discussion that absence of a spherical BPS state is not enough, because multi-centred BPS composites could still exist for the same charges; this is a concrete gap that a systematic search over charge vectors could close.
Original abstract

We study the attractor mechanism for extremal non-BPS black holes with an infinite throat near horizon geometry, developing, as we do so, a physical argument as to why such a mechanism does not exist in non-extremal cases. We present a detailed derivation of the non-supersymmetric attractor equation. This equation defines the stabilization of moduli near the black hole horizon: the fixed moduli take values specified by electric and magnetic charges corresponding to the fluxes in a Calabi Yau compactification of string theory. They also define the so-called double-extremal solutions. In some examples, studied previously by Tripathy and Trivedi, we solve the equation and show that the moduli are fixed at values which may also be derived from the critical points of the black hole potential.

The compiled record

The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Compiled by classifier-1.13-20260917 via OpenRouter, question bank abstract-p1-20260923, 2026-09-23: 1 request, 4,305 input tokens, $0.0002 reported.

What the abstract itself states, as probabilities: claims first 0.05 · states limitation 0.70 · human participants 0.01 · controlled comparison 0.05 · randomized assignment 0.01 · states quantitative result 0.04 · compares with prior results 0.81 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v2. Results and the main claim are underlined; .

We study the attractor mechanism for extremal non-BPS black holes with an infinite throat near horizon geometry, developing, as we do so, a physical argument as to why such a mechanism does not exist in non-extremal cases. We present a detailed derivation of the non-supersymmetric attractor equation. This equation defines the stabilization of moduli near the black hole horizon: the fixed moduli take values specified by electric and magnetic charges corresponding to the fluxes in a Calabi Yau compactification of string theory. They also define the so-called double-extremal solutions. In some examples, studied previously by Tripathy and Trivedi, we solve the equation and show that the moduli are fixed at values which may also be derived from the critical points of the black hole potential.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#sentencerolethe authors' own workstates the main conclusionstrength
s0 We study the attractor mechanism for extremal non-BPS black holes with an infinite throat near horizon geometry, developing, as we do so, a physical argument as to why such a mechanism does not exist in non-extremal cases. contribution 0.99 0.93 0.37 asserted 0.99
s1 We present a detailed derivation of the non-supersymmetric attractor equation. contribution 0.95 0.96 0.19 asserted 0.99
s2 This equation defines the stabilization of moduli near the black hole horizon: the fixed moduli take values specified by electric and magnetic charges corresponding to the fluxes in a Calabi Yau compactification of string theory. interpretation 0.57 0.58 0.27 asserted 1.00
s3 They also define the so-called double-extremal solutions. interpretation 0.69 0.37 0.09 asserted 1.00
s4 In some examples, studied previously by Tripathy and Trivedi, we solve the equation and show that the moduli are fixed at values which may also be derived from the critical points of the black hole potential. result 0.73 0.82 0.12 hedged possibility 0.56

What kind of paper the classifier reports this is: theoretical result 1.00 · evidence from proof or derivation 1.00.

What was examined, and what was not

sources read
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  • references and citing sentences
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  • C citations
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Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

Figures
Figure 1. On the left there is an Euclidean section of the near horizon “cigar” geometry of the non￾extremal black holes with non-vanishing temperature. On the right there is an Euclidean section of an infinite throat near horizon geometry of the extremal black holes with vanishing temperature. We start by deriving the equations of motion for the scalar field from the Lagrangian: L
Figure 2. Evolution of the dilaton field e −2z for various initial conditions at ρ = 0 (r = ∞) to a common fixed point at ρ = −∞ (r = 0) where ρ = − 1 r . The special case of the horizontal line represents a double-extremal black hole. We call these black holes double-extremal since they pick up the values of the moduli at infinity that extremize the black hole mass; values that are equal to those at the horizon. There is no energy stored in the scalars, so ∂z ∂τ = 0 everywhere. While for the BPS case DZ = 0 everywhere, the most general conditions are that double-extremal black holes (BPS

Figures reproduced from arXiv:hep-th/0602005 by the authors.

References
How the literature uses it

45 arXiv papers cite this in 74 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it · 41 sentences without a confident label

Uses its method or tool 3 papers
Uses its data or values 1 paper
  • From ([ref]), the superpotential for this system reads [equation] The attractor values of the moduli in the non-SUSY branch have been previously found in [ref] by minimizing the black hole potential $V_BH$ and they are given by [equation] As in the previous example, the signs of the solutions are chosen such that the Kähler volume is positive.

    New Perspectives on Attractor Flows and Trees from CFT · D0-D4 system · 0.81

Compares with it 1 paper
  • Because of the factorized structure of the $stu$ model, the attractor equations [ref] [equation] can be rewritten as a set of equations [equation] which coincide with the $N=8$ algebraic attractor equations [equation] for the four complex eigenvalues $z_i$ of $Z_AB$ [ref] .

    Universality of the superpotential for d = 4 extremal black holes · Connection with $N=8$ · 0.84

Cites it as support 2 papers
Cites it as background 24 papers

Discussion

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