REVIEW
Supersymmetry and Attractors
High Energy Physics - Theory · Submitted 26 Feb 1996 · 31 references
Pith's verdict: The attractor paper: S = π|Z_fix|² is derived cleanly for N=2, and the thin spots are all in the N=8 and 5d asides, not the main claim.
T0 · AI review
Why Pith says this
Highlight any text to comment on it.
Referee report
The paper
The paper claims
The horizon area of an extremal supersymmetric black hole equals the square of its central charge evaluated where that charge is extremized over the scalar fields, so the entropy depends only on electric and magnetic charges.
The reading
What carries the argument
The load-bearing object is the central charge $Z = e^{K/2}(X^Lambda q_Lambda - F_Lambda p^Lambda)$, built from the holomorphic symplectic sections of special geometry and the electric and magnetic charge vector. Its modulus equals the ADM mass of a half-supersymmetric state, and its covariant derivative $D_i Z$ measures how far the scalar configuration is from the attractor. Setting $D_i Z = 0$ produces an algebraic relation expressing the charges in terms of the sections, $p^Lambda = i(bar Z L^Lambda - Z bar L^Lambda)$ and similarly for $q_Lambda$, which shows the fixed point is determined by charge ratios up to a Kähler gauge choice. The symplectic invariant $I_1 = |Z|^2 + |D_i Z|^2$, written as $-tfrac12 P^t M(N) P$ with the vector kinetic matrix at the fixed point, then delivers the area in a manifestly duality-invariant form.
Extended reading notes
Core claim
The paper's central claim is that the horizon area of an extremal $N=2$ black hole in four dimensions is fixed by a variational principle in the moduli space: extremize the modulus of the central charge, $|Z(z,bar z,p,q)|$, with respect to the scalar fields, and the value at the extremum gives the entropy through $S = A/4 = |Z_{fix}|^2$. The condition for the extremum is the duality-covariant equation $D_i Z = (partial_i + K_i/2) Z = 0$, which is exactly the condition that the vector-multiplet field strengths vanish near the horizon and that the scalars sit at a fixed point of attraction. Because the fixed-point equations are homogeneous in the charges, the critical moduli depend only on charge ratios, so the area forgets the asymptotic values of the coupling constants. The authors further show that the near-horizon geometry is of Bertotti-Robinson type and is conformally flat, which is what restores the second supersymmetry there, doubling the unbroken supersymmetry from one half to all of $N=2$. Hypermultiplets drop out of the area formula entirely.
Load-bearing premise
The derivation assumes that the equation $D_i Z = 0$ actually has a solution and that the stationary point so found is a minimum; the paper's own footnote concedes that neither point is established in general.
Editorial extensions
If this is right
- Every extremal $N=2$ black hole entropy becomes computable from its electric and magnetic charges alone, with no need to know the asymptotic values of the scalar fields.
- The result gives a model-independent macroscopic formula that any microscopic state count must reproduce, and it is manifestly invariant under electric-magnetic duality rotations.
- The attractor mechanism extends to $N=4$ and $N=8$ supergravity, where the area reduces to expressions such as $sqrt{|p_0 p_1|}$ or $sqrt{|m_0 m_2 e_1 e_3|}$ built from products of charges.
- In five dimensions the same extremization of the central charge yields $S sim Z^{3/2}$, reproducing the charge-product formulas discussed for five-dimensional black holes.
- Hypermultiplet scalars do not enter the area formula, so the entropy is insensitive to that whole sector of the theory.
Reading between the lines
- If the extremum is always a minimum, the moduli space near the horizon acts like a basin of attraction whose shape is set by the charges, which suggests the entropy is a kind of distance function on the charge lattice rather than a dynamical quantity.
- The same variational structure looks like it should survive beyond static extremal holes, for instance stationary rotating ones, where the relevant function would be extremized over moduli with the angular momentum held fixed.
- Because the area is invariant under duality but the underlying charges are discrete, the formula is a natural bridge to microscopic counting: any candidate microstate degeneracy must be a duality-invariant function of the same charge invariants.
- The conformal flatness of the near-horizon geometry is doing more work than the paper exploits: it hints that the near-horizon region is a maximally symmetric vacuum, so the attractor fixed point may be a statement about which vacua a given charge configuration can interpolate between.
Original abstract
We find a general principle which allows one to compute the area of the horizon of N=2 extremal black holes as an extremum of the central charge. One considers the ADM mass equal to the central charge as a function of electric and magnetic charges and moduli and extremizes this function in the moduli space (a minimum corresponds to a fixed point of attraction). The extremal value of the square of the central charge provides the area of the horizon, which depends only on electric and magnetic charges. The doubling of unbroken supersymmetry at the fixed point of attraction for N=2 black holes near the horizon is derived via conformal flatness of the Bertotti-Robinson-type geometry. These results provide an explicit model independent expression for the macroscopic Bekenstein-Hawking entropy of N=2 black holes which is manifestly duality invariant. The presence of hypermultiplets in the solution does not affect the area formula. Various examples of the general formula are displayed. We outline the attractor mechanism in N=4,8 supersymmetries and the relation to the N=2 case. The entropy-area formula in five dimensions, recently discussed in the literature, is also seen to be obtained by extremizing the 5d central charge.
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.
The abstract, sentence by sentence
We find a general principle which allows one to compute the area of the horizon of N=2 extremal black holes as an extremum of the central charge. One considers the ADM mass equal to the central charge as a function of electric and magnetic charges and moduli and extremizes this function in the moduli space (a minimum corresponds to a fixed point of attraction). The extremal value of the square of the central charge provides the area of the horizon, which depends only on electric and magnetic charges. The doubling of unbroken supersymmetry at the fixed point of attraction for N=2 black holes near the horizon is derived via conformal flatness of the Bertotti-Robinson-type geometry. These results provide an explicit model independent expression for the macroscopic Bekenstein-Hawking entropy of N=2 black holes which is manifestly duality invariant. The presence of hypermultiplets in the solution does not affect the area formula. Various examples of the general formula are displayed. We outline the attractor mechanism in N=4,8 supersymmetries and the relation to the N=2 case. The entropy-area formula in five dimensions, recently discussed in the literature, is also seen to be obtained by extremizing the 5d central charge.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We find a general principle which allows one to compute the area of the horizon of N=2 extremal black holes as an extremum of the central charge. | contribution 0.51 | 0.95 | 0.80 | asserted 1.00 |
| s1 | One considers the ADM mass equal to the central charge as a function of electric and magnetic charges and moduli and extremizes this function in the moduli space (a minimum corresponds to a fixed point of attraction). | method 0.96 | 0.48 | 0.12 | asserted 0.95 |
| s2 | The extremal value of the square of the central charge provides the area of the horizon, which depends only on electric and magnetic charges. | result 1.00 | 0.83 | 0.40 | asserted 1.00 |
| s3 | The doubling of unbroken supersymmetry at the fixed point of attraction for N=2 black holes near the horizon is derived via conformal flatness of the Bertotti-Robinson-type geometry. | result 0.91 | 0.84 | 0.07 | asserted 1.00 |
| s4 | These results provide an explicit model independent expression for the macroscopic Bekenstein-Hawking entropy of N=2 black holes which is manifestly duality invariant. | result 0.61 | 0.89 | 0.48 | asserted 1.00 |
| s5 | The presence of hypermultiplets in the solution does not affect the area formula. | result 0.99 | 0.77 | 0.05 | asserted 1.00 |
| s6 | Various examples of the general formula are displayed. | contribution 0.89 | 0.85 | 0.02 | asserted 0.97 |
| s7 | We outline the attractor mechanism in N=4,8 supersymmetries and the relation to the N=2 case. | contribution 0.92 | 0.74 | 0.05 | asserted 0.89 |
| s8 | The entropy-area formula in five dimensions, recently discussed in the literature, is also seen to be obtained by extremizing the 5d central charge. | result 0.80 | 0.67 | 0.06 | asserted 0.97 |
What was examined, and what was not
- arXiv listing abstract v3
- full text
- figures and tables
- references and citing sentences
- relations to other papers
- P abstract
- S sections
- T body sentences
- C citations
- R cross-paper relations
Figures
Figures reproduced from arXiv:hep-th/9602136 by the authors.
References
How later papers used it
186 later papers cite it
2 later papers by other authors are listed below: 1 built on it and 1 used its method or tool.
Builds on it 1 of 4 papers with this label
-
Used this to uncover new general properties of near horizon regions of small black holes, regarded as an extension of the attractor mechanism for large extremal black holes.
Fake supersymmetry versus Hamilton-Jacobi (2012) · 0.99 · paraphrased: the licence does not allow quoting
Uses its method or tool 1 of 8 papers with this label
-
Used this paper's attractor equations to fix the moduli at the black hole horizon in terms of the charges and compute the entropy.
A note on modular invariant species scale and potentials (2023) · 0.90 · paraphrased: the licence does not allow quoting
How the literature uses it
175 arXiv papers cite this in 247 sentences
Papers citing it · 136 sentences without a confident label
Builds on it 4 papers
-
We are interested in finding a generalization of the attractor mechanism of [ref] for cases which include not only constant values of the scalars $ϕ^i$ and tangent space field strengths $F_ab= e_a^μ e_b^ν F_μν$ (fluxes), but also constant values of the tangent space vectors $A_a= e^μ_a A_μ$.
Generalized Attractor Points in Gauged Supergravity · Generalized Attractors in D=4 Supergravity · 0.95
-
We use this in section [ref] to uncover new general properties of the near horizon regions of small black holes, which can be regarded as an extension of the attractor mechanism for large extremal black holes [ref] .
Fake supersymmetry versus Hamilton-Jacobi · Introduction · 0.99
-
In [ref] the authors present a generalization of the well-known black hole attractor mechanism in $N=2$ ungauged supergravity introduced in [ref] to extremal static black holes in four-dimensional $N=2$ $FI$ supergravity coupled to abelian vector multiplets.
Supersymmetric objects in gauged supergravities · Attractors and Hypermultiplets · 0.89
Uses its method or tool 9 papers
-
It turns out that in these cases known techniques (the “attractor mechanism" [ref] ) available from study of macroscopic black holes and black strings for large charges (where we rescale the cycle class by a large integer) can give reliable predictions about properties of non-BPS objects and these, in turn, lead to predictions about existence, stability, and asymptotic count for for minimal volume 2- and 4-cycles in the Calabi-Yau.
Non-Holomorphic Cycles and Non-BPS Black Branes · Introduction · 0.95
-
To find the area correction $δA_h$ we use the attractor mechanism [ref] .
Derivative Corrections to Extremal Black Holes with Moduli · The area correction via the attractor mechanism · 0.99
-
The key ingredient is the lattice Zariski decomposition $b_0=P+N$ of the gravitational charge $b_0$, whose physical content is the attractor flow of the gravitational BPS black string [ref] .
Intersection Bounds for BPS Strings in Six-Dimensional Supergravity · Discussion · 0.80
Compares with it 2 papers
-
Furthermore, it is easy to see that in the limit $g →0$ where the gauging vanishes one recovers the well-known first order attractor flow equations of black holes in ungauged $N=2$ supergravity [ref] .
Static supersymmetric black holes in AdS_4 with spherical symmetry · BPS conditions and attractor flow · 0.80
-
With this ansatz, the equations give = -2 = + i = i/R e^iψ_0 These equations are in fact identical to the attractor equations for solutions of the form $AdS_2×S^2$ in ungauged $=2$ supergravity [ref] with the obvious replacement of the gauging parameters $$ with charges $$.
Supersymmetric Black Holes in AdS4 from Very Special Geometry · General $AdS_4$ solutions · 0.87
Cites it as background 80 papers
-
The entropy function method was developed by Sen [ref] , and was first applied for the computation of the entropy and the study of the attractor mechanism [ref] for black holes with spherical symmetry.
Conductivities from attractors · Entropy function · 0.88
-
The first one is the “background”: our starting point is an AdS$_2$ solution, characterized by a set of electric and magnetic charges, and the six scalar fields are controlled by the attractor mechanism [ref] .
Near-AdS$_2$ Spectroscopy: classifying the spectrum of operators and interactions in $\mathcal{N} = 2$ 4D supergravity · Introduction · 0.87
-
In fact, by defining the Freudenthal transformation acting on the e.m. black hole charges as [equation] it holds that [ref] [equation] In this framework, the Freudenthal map ([ref]) is anti-involutive since it can be recast in the following form: [equation] where $ℳ_H(𝒬)$ denotes the matrix $ℳ$ of special Kähler geometry (see e.g. [ref] and Refs. therein), evaluated at the (unique) event horizon of the extremal black hole (at which the attractor mechanism [ref] takes place; see also ).
Near-Extremal Freudenthal Duality · $T=0$ : invariance of extremal entropy · 0.86
Discussion
Disagree with the review, or know something it missed? Leave a comment, highlight any passage above to comment on it, or challenge this review formally.