REVIEW
Distributions of nonsupersymmetric flux vacua
High Energy Physics - Theory · Submitted 19 Nov 2004 · 37 references
Pith's verdict: The eigenvector reformulation is exact and useful; the M*^12 scaling is an honest order-of-magnitude estimate whose exponent depends on an ensemble assumption the authors themselves flag as unproven.
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Referee report
The paper
The paper claims
Nonsupersymmetric flux vacua are counted by eigenvectors of a Hessian, and low-scale breaking is suppressed
The reading
What carries the argument
The load-bearing object is the matrix $M$ of Eq. (2.15), a hermitian matrix built from the symmetric matrix $Z_{AB} = D_A D_B W$ and the phase of $W$, obeying the symmetry conditions $M = -0_3 M 0_3 = -0_2 M^* 0_2$. Its eigenvalues come in $+0,-0$ pairs, and its eigenvectors, written as $0^+_a$ and $0^-_a$, are approximate mass eigenstates of the bosonic mass matrix when $|F|$ is small. Solving $dV=0$ becomes the eigenvalue condition $2|W| = 0_1$, with $F$ proportional to the corresponding eigenvector. The symmetry conditions place $M$ in the CI ensemble of Altland and Zirnbauer, whose measure the authors write explicitly as $[dU] 0_a d(0_a^2) 0_{a<b} |0_a^2 - 0_b^2|$; the factor $0_a d(0_a^2)$ is what converts a small eigenvalue into a factor of $0^2$ in the vacuum count, and the Vandermonde-like product is what makes degenerate eigenvalues cost codimension. The paper then uses this to argue that higher branches with $k$-fold degenerate eigenvalues sit at real codimension $k(k-1)/2$ and so do not contribute to the leading large-$L$ asymptotics, except in special cases where the matrices $0Z/0|Z_i|$ commute after a similarity transformation.
Extended reading notes
Core claim
The central claim is that the distribution of nonsupersymmetric flux vacua is, to a good approximation, the distribution of supersymmetric vacua multiplied by computable correction factors, and that those factors can be read off from the eigenvalue statistics of $Z_{AB} = D_A D_B W$. The derivation runs in three steps. First, the equations $dV=0$ are rewritten as a linear problem $N(W,Z) F = 0$, whose solutions are eigenvectors of a hermitian matrix $M$ built from $Z$; a non-supersymmetric vacuum sits at $2|W| = |Z|$'s smallest eigenvalue, and the phase of $F$ is fixed, so the measure is $dF$ rather than $d^2F$. Second, the density of such vacua is written as $|det H|$ times a correction factor involving the two squared masses in the supersymmetry-breaking direction, where $H$ is the same matrix whose determinant weights the supersymmetric count. Third, evaluating the correction factors in the generic ensemble gives $N(M_{susy} < M_*, 0 < M_*^{12}$ for pure $F$ breaking with $M_*$ small. The authors are explicit that this is a sum of four effects of comparable size — the fixed phase, the $d(0^2)$ distribution of the smallest eigenvalue, a factor $F^2$ from $det V''$, and a further $F^2$ from the metastability tuning — and that no single one of them dominates. They also treat the case where a small $D$-term lifts supersymmetric vacua, finding a distribution that instead favors low breaking scales, going roughly as $1/0 M_*$.
Load-bearing premise
The $M_*^{12}$ scaling assumes that the matrix of second superpotential derivatives behaves like a generic member of the CI random-matrix ensemble, so that a small eigenvalue is distributed as $d(0^2)$ with no special structure — an assumption the paper's own tractable examples violate.
Editorial extensions
If this is right
- The naive expectation that independent hidden sectors add their supersymmetry breaking and push the distribution toward high scales is not borne out: the different $F$-terms are independently distributed only if the sectors are completely decoupled.
- A low supersymmetry breaking scale is disfavored for pure $F$ breaking once the cosmological constant is tuned near zero, by a factor of order $M_*^8$ relative to the untuned count.
- Supersymmetry breaking by a small $D$-term, such as an antibrane near a conifold, produces a distribution falling only as $1/0 M_*$, so the two mechanisms point in opposite directions and their relative abundance is what decides the question.
- The universal $-2|W|^2$ term in the bosonic mass matrix destabilizes vacua with light fermions and $|D|, |W| 00 |F|$, removing a large class of otherwise realistic-looking vacua.
- Because the mass-matrix determinant enters as a weight, the general expectation that bosons much lighter than the natural scale of the potential are disfavored is made quantitative.
Reading between the lines
- If the same eigenvalue-repulsion logic applies to the Kähler sector once it is properly stabilized, then the $M_*^{12}$ suppression may be partly offset by the extra measure factors that sector contributes, which the paper explicitly sets aside.
- The result suggests a sharper statement than the paper makes: the tuning of the cosmological constant, rather than the dynamics of supersymmetry breaking, is the dominant selector among flux vacua, which would make anthropic-style weighting of $0$ less necessary than usually assumed.
- The paper's own counterexamples — the one-modulus conifold with its see-saw determinant, and the orbifold with commuting generators — suggest a practical test: survey the eigenvalue spacing of $Z$ across many explicitly constructible Calabi-Yau moduli spaces and see whether the CI prediction holds or whether commuting structure is common.
- If explicit enumeration of quantized fluxes at moderate $L$ confirms the continuous approximation for small $F$, that would validate the whole approach; if it instead cuts off small $F$ as the authors suspect, the suppression would be even stronger than $M_*^{12}$.
Original abstract
We continue the study of the distribution of nonsupersymmetric flux vacua in IIb string theory compactified on Calabi-Yau manifolds, as in hep-th/0404116. We show that the basic structure of this problem is that of finding eigenvectors of the matrix of second derivatives of the superpotential, and that many features of the results are determined by features of the generic ensemble of such matrices, the CI ensemble of Altland and Zirnbauer originating in mesoscopic physics. We study some simple examples in detail, exhibiting various factors which can favor low or high scale supersymmetry breaking.
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 continue the study of the distribution of nonsupersymmetric flux vacua in IIb string theory compactified on Calabi-Yau manifolds, as in hep-th/0404116. We show that the basic structure of this problem is that of finding eigenvectors of the matrix of second derivatives of the superpotential, and that many features of the results are determined by features of the generic ensemble of such matrices, the CI ensemble of Altland and Zirnbauer originating in mesoscopic physics. We study some simple examples in detail, exhibiting various factors which can favor low or high scale supersymmetry breaking.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We continue the study of the distribution of nonsupersymmetric flux vacua in IIb string theory compactified on Calabi-Yau manifolds, as in hep-th/0404116. | background 0.86 | 0.46 | 0.04 | asserted 0.65 |
| s1 | We show that the basic structure of this problem is that of finding eigenvectors of the matrix of second derivatives of the superpotential, and that many features of the results are determined by features of the generic ensemble of such matrices, the CI ensemble of Altland and Zirnbauer originating in mesoscopic physics. | contribution 0.47 | 0.90 | 0.62 | asserted 1.00 |
| s2 | We study some simple examples in detail, exhibiting various factors which can favor low or high scale supersymmetry breaking. | contribution 0.81 | 0.92 | 0.08 | asserted 0.95 |
What was examined, and what was not
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References
How later papers used it
85 later papers cite it
1 later paper by other authors is listed below: 1 built on it.
Builds on it 1 of 2 papers with this label
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Extended this paper's work by taking a specific unit vector aligned in the two sGoldstino directions.
Bounds on Scalar Masses in Theories of Moduli Stabilization (2010) · 0.99 · paraphrased: the licence does not allow quoting
How the literature uses it
82 arXiv papers cite this in 144 sentences
Papers citing it · 96 sentences without a confident label
Contests it 1 paper
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This is the case for the $STU$-model considered in [ref] , but for the moduli space of a more general Calabi-Yau compactification, $D_k( κ_ijl e^K_c.s. ) ≠0$.[We note that, contrary to an aside assertion of [ref] , generically $D_k( κ_ijl e^K_c.s. ) ≠0$ in the large complex structure limit of the compactification manifold. ]
A New Class of de Sitter Vacua in Type IIB Large Volume Compactifications · Metastable vacua · contest 0.72
Builds on it 2 papers
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Extending the work of [ref] , we take $ξ= (G^j̅ c G^j ) / √(3(1 + |c|^2))$ for $c ∈ℂ$, which is aligned in the (moduli components of the) two sGoldstino directions $η= G^i ϕ_i$ and $η̅ = G_i ϕ^i$.
Bounds on Scalar Masses in Theories of Moduli Stabilization · Supergravity and Moduli Masses · 0.99
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We will show this in the next section by extending some of the general techniques which were developed in the context mainly of IIB flux vacua in [ref] .
Phenomenology from the Landscape of String Vacua · $G_2$ holonomy Statistics · 0.80
Uses its method or tool 2 papers
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We prove this theorem by adapting methods of Douglas and collaborators used to count flux vacua and attractor black holes [ref] .[As will be clear, this is a bit overkill.
Recounting Special Lagrangian Cycles in Twistor Families of K3 Surfaces. Or: How I Learned to Stop Worrying and Count BPS States · More precise statement of the problem · 1.00
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More specifically, we use the techniques derived in the seminal papers [ref] , whose only assumption is the continuous flux approximation.
Towards a complete mass spectrum of type-IIB flux vacua at large complex structure · Introduction · 1.00
Compares with it 7 papers
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The power-law distribution of gravitino masses in ([ref]) and ([ref]) for KKLT and perturbatively stabilised vacua reproduces the results of [ref] which were based on the assumption of a democratic distribution of complex structure F-terms caused by the uniform distribution of $|W_0|$, as we have reviewed in Sec. [ref].
Moduli Stabilisation and the Statistics of SUSY Breaking in the Landscape · Interplay with previous results · 0.93
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Comparing to the earlier works [ref] where explicit interactions among the moduli and fluxes are not taken into account, we see that the statistical preference for a small $Λ$ (and at times some scalar masses) emerges only when couplings are included.
Linking Light Scalar Modes with A Small Positive Cosmological Constant in String Theory · Conclusion and Remarks · 0.99
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For nonsupersymmetric vacua the results were less detailed, mainly because the constraint $V'=0$ is quadratic in $F$, and, unlike the situation in [ref] , no regime exists in which the equations can be linearized.
Phenomenology from the Landscape of String Vacua · Model Kähler Potentials and Exact Solutions · 0.80
Cites it as support 3 papers
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But such tuning greatly decreases the size of the allowed parameter region [ref] .
Vacuum statistics and parameter tuning for F-term supersymmetry breaking · One-field approximation · 0.97
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Underlying this question is a view that supersymmetric states might be exceptional, a view which finds support in the work of Douglas and Denef [ref] , indicating that small supersymmetry breaking is rare.
Classical and Quantum Stability in Putative Landscapes · Conclusions · 0.97
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Such a hierarchy is quite unnatural for a broad class of models in which moduli stabilization sets the scale of supersymmetry breaking [ref] .
Dark Matter Production Mechanisms with a Non-Thermal Cosmological History - A Classification · Motivation and Introduction · 0.97
Cites it as background 27 papers
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More specifically, what can we say about the set from the point of view of the statistical approach to string phenomenology [ref] (see [ref] for studies in various settings in this context)?
On the Search for Low $W_0$ · Introduction · 0.93
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The probability of obtaining a $dS$ vacuum in string theory was previously considered in [ref] .
A Global View on The Search for de-Sitter Vacua in (type IIA) String Theory · Discussions · 0.96
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A complementary line of inquiry, starting with the seminal work [ref] , has been to frame the question in terms of statistical distributions in the landscape of flux vacua [ref] .
Moduli Stabilisation and the Statistics of SUSY Breaking in the Landscape · Introduction · 0.95
Discussion
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