REVIEW
Quantization of Four-form Fluxes and Dynamical Neutralization of the Cosmological Constant
High Energy Physics - Theory · Submitted 18 Apr 2000 · 52 references
Pith's verdict: The paper that turned the cosmological constant into a discrete landscape variable, and the core argument — flux quantization plus a multi-flux grid — survives rereading; the soft parts are the frozen charges and the qualitative reheating story.
T0 · AI review
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Referee report
The paper
The paper claims
The paper argues that four-form flux is quantized, so the cosmological constant takes only discrete values, and that with enough independent fluxes those values become dense enough to include the observed one.
The reading
What carries the argument
The load-bearing object is the discretuum: the set of allowed vacuum energies $lambda = lambda_{bare} + frac{1}{2}sum_{i=1}^{J} n_i^2 q_i^2$, viewed as the squared radii of integer lattice points in $J$ dimensions with spacings $q_i$. Cancellation of a negative bare cosmological constant becomes a geometric question, whether a shell of radius $sqrt{2|lambda_{bare}|}$ and width $Delta r = |2lambda_{bare}|^{-1/2}Delta lambda$ contains a lattice point, and the answer gives the level spacing in Eq. (2.26). What makes the grid fine enough is the generalized Dirac quantization condition applied to the dual zero-form, $F_0 = en/Z$, which fixes the $q_i$ in terms of membrane charges and compactification volumes. The second piece of machinery is the Brown-Teitelboim dynamics: membrane nucleation moves the integers $n_i$ down by one, so the cosmology is a random walk on the same grid, and de Sitter thermal fluctuations supply the inflaton displacement needed for reheating.
Extended reading notes
Core claim
The central claim is that four-form flux is quantized not only in the sense that its integral over a closed four-manifold is an integer multiple of $2/e$, but that the flux itself takes discrete values $c = en/Z$ with $n$ an integer. The authors argue this from the dual zero-form: when a theory has both electric and magnetic sources, the dual field strength evaluated at a point must be quantized, and in an M-theory compactification on a seven-manifold this follows from the M5-brane charge condition. The immediate consequence is bad for the old idea that a single flux cancels the bare cosmological constant, because the spacing is enormous compared with $10^{-120}M_{Pl}^4$. The rescue is multiplicity. With $J$ independent fluxes the vacuum energy is $lambda = lambda_{bare} + frac{1}{2}sum_i n_i^2 q_i^2$, so the allowed values are squared radii of points on a $J$-dimensional grid; if the charges are incommensurate, a thin shell of radius $sqrt{2|lambda_{bare}|}$ and width set by the observational bound will contain a grid point. The authors estimate that of order 100 fluxes suffice at the GUT or Planck scale, while four or five suffice if the fundamental scale is near a TeV with large extra dimensions. They then extend the Brown-Teitelboim membrane-nucleation cosmology to many fluxes: starting from generic initial conditions with positive vacuum energy, repeated nucleation is a random walk on the grid that populates every point with $lambda > 0$, so regions with $lambda$ in the Weinberg window exist and expand eternally. They further argue that the Gibbons-Hawking temperature of the pre-final de Sitter phase can keep an inflaton field randomly displaced until the final nucleation, after which it rolls and reheats, addressing the empty-universe problem.
Load-bearing premise
The whole density estimate assumes the membrane charges are frozen, incommensurate constants; the authors explicitly set the moduli problem aside and work in an artificial model with fixed charges, so if the compactification volume and background moduli are not stabilized independently of the fluxes, the flux energy is a potential for those moduli rather than a fixed grid.
Editorial extensions
If this is right
- The cosmological constant becomes a discrete label of a vacuum rather than a continuous parameter, so exact zero is not special and a small nonzero value is generic.
- The spectrum of allowed vacuum energies is computable from the charges of the compactification's three-cycles, giving a concrete target for model building in M theory.
- Decay rates out of a small-$lambda$ phase are estimated to be negligible, so the selected vacuum survives long enough to host structure.
- In large-extra-dimension scenarios the same fluxes that make membrane charges small tie the hierarchy problem and the cosmological constant problem to a single problem: stabilizing large radii.
Reading between the lines
- If the discretuum is real, the number of vacua with $lambda$ in the observational window grows with the number of three-cycles, which points toward a statistical prediction for the distribution of $lambda$ rather than a unique value.
- The mechanism predicts that any residual cosmological constant is nonzero and set by the nearest grid point, so a measured $Lambda$ near the window is consistent with the picture but not sharply predicted by it.
- The natural follow-up is a compactification in which the fluxes both stabilize the moduli and supply the discretuum; that would turn the density estimate from a plausibility argument into a computation.
- Because the same nucleation random walk populates every flux configuration, other flux-dependent couplings may also be selected environmentally, not just the vacuum energy.
Original abstract
A four-form gauge flux makes a variable contribution to the cosmological constant. This has often been assumed to take continuous values, but we argue that it has a generalized Dirac quantization condition. For a single flux the steps are much larger than the observational limit, but we show that with multiple fluxes the allowed values can form a sufficiently dense `discretuum'. Multiple fluxes generally arise in M theory compactifications on manifolds with non-trivial three-cycles. In theories with large extra dimensions a few four-forms suffice; otherwise of order 100 are needed. Starting from generic initial conditions, the repeated nucleation of membranes dynamically generates regions with a cosmological constant in the observational range. Entropy and density perturbations can be produced.
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
A four-form gauge flux makes a variable contribution to the cosmological constant. This has often been assumed to take continuous values, but we argue that it has a generalized Dirac quantization condition. For a single flux the steps are much larger than the observational limit, but we show that with multiple fluxes the allowed values can form a sufficiently dense `discretuum'. Multiple fluxes generally arise in M theory compactifications on manifolds with non-trivial three-cycles. In theories with large extra dimensions a few four-forms suffice; otherwise of order 100 are needed. Starting from generic initial conditions, the repeated nucleation of membranes dynamically generates regions with a cosmological constant in the observational range. Entropy and density perturbations can be produced.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | A four-form gauge flux makes a variable contribution to the cosmological constant. | background 1.00 | 0.12 | 0.05 | asserted 1.00 |
| s1 | This has often been assumed to take continuous values, but we argue that it has a generalized Dirac quantization condition. | contribution 0.56 | 0.51 | 0.33 | asserted 0.60 |
| s2 | For a single flux the steps are much larger than the observational limit, but we show that with multiple fluxes the allowed values can form a sufficiently dense `discretuum'. | result 0.83 | 0.89 | 0.31 | asserted 0.99 |
| s3 | Multiple fluxes generally arise in M theory compactifications on manifolds with non-trivial three-cycles. | background 0.94 | 0.15 | 0.03 | asserted 0.96 |
| s4 | In theories with large extra dimensions a few four-forms suffice; otherwise of order 100 are needed. | result 0.84 | 0.63 | 0.06 | asserted 0.97 |
| s5 | Starting from generic initial conditions, the repeated nucleation of membranes dynamically generates regions with a cosmological constant in the observational range. | result 0.74 | 0.79 | 0.52 | asserted 0.99 |
| s6 | Entropy and density perturbations can be produced. | result 0.88 | 0.55 | 0.05 | hedged possibility 0.72 |
What was examined, and what was not
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Figures
Figures reproduced from arXiv:hep-th/0004134 by the authors.
References
How later papers used it
443 later papers cite it
2 later papers by other authors are listed below: 1 built on it and 1 compared its own results with it.
Builds on it 1 of 6 papers with this label
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Here we show how it is generalised to a much wider class of models which could, in principle, include the Bousso-Polchinski set-up [ref] .
The cosmological constant is probably still zero (2023) · Nucleation rates · 0.97
Compares with it 1 of 11 papers with this label
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Compared its own scenarios, which rely on a single four-form flux of electroweak scale to get both the Higgs mass and the cosmological constant at right scales, with this paper's proposal where multiple four-form fluxes were introduced for scanning the cosmological constant with the precision of the observed value.
The Selfish Higgs and Reheating (2019) · 0.99 · paraphrased: the licence does not allow quoting
How the literature uses it
420 arXiv papers cite this in 641 sentences
Papers citing it · 409 sentences without a confident label
Contests it 1 paper
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However the analysis in [ref] does not take moduli stabilization into account and the resultant distribution of quantized fluxes does not imply the preference of a small cosmological constant.
Probability of Vacuum Stability in Type IIB Multi-K\"ahler Moduli Models · Introduction · contest 0.84
Builds on it 6 papers
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What we try to do in the next section is to modify this latter mechanism by including a larger number $J$ of different four-forms in order to avoid the gap problem, in the same spirit of the BP extension of the BT mechanism [ref] .
Environmental selection of the cosmological constant and electroweak scales · Four-forms and environmental selection of the electroweak scale · 0.94
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Here we show how it is generalised to a much wider class of models which could, in principle, include the Bousso-Polchinski set-up [ref] .
The cosmological constant is probably still zero · Nucleation rates · 0.97
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In its simplest incarnation, our approach is a generalization of the idea pioneered in [ref] about discharging cosmological constant by nonperturbative membrane nucleation processes, and also benefits from results of [ref] .
Implications of Weak Gravity Conjecture for de Sitter Decay by Flux Discharge · Introduction · 0.96
Uses its data or values 5 papers
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If current estimates of the number of vacua [ref] hold up, i.e., if $log_10 N$ is of order hundreds,[The number of anthropic vacua, $N̅$, may be smaller by dozens or even hundreds of orders of magnitude than the total number of vacua, $N$, for low-energy reasons that are unrelated to the cosmological constant or curvature and so are not included in out analysis.
Geometric origin of coincidences and hierarchies in the landscape · Positive cosmological constant · 0.85
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The number of flux vacua on a given CY background space is very huge [ref] : $N_vac∼10^500$.
String Landscape and the Standard Model of Particle Physics · Moduli stabilization · 0.92
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For example, a typical of tunneling probability (using the thin wall Coleman-De Luccia result) in the Bousso-Polchinski scenario is $∼e^-100$ [ref] .
Rapid Tunneling and Percolation in the Landscape · Percolation in the Landscape: Efficient Tunneling and Preferred Paths · 0.91
Compares with it 9 papers
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Note that for the benchmark point of $J=100$ of [ref] we find that $q_GL ≈q_BP/2$ and indication that a simultaneous solution to the CC and EW hierarchy problems can be found in the presence of a mild hierarchy between $v$ and $Λ^1/4$ at the expense of introducing a weak coupling between the four-forms and the Higgs scalar.
Environmental selection of the cosmological constant and electroweak scales · Arbitrary J · 0.98
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This is a significant departure from the anthropic arguments usually presented for the Bousso-Polchinski set-up [ref] .
The cosmological constant is probably still zero · The Bousso-Polchinski set-up · 0.83
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However there are important technical differences when we compare to those models since in our theory the bulk cosmological constant depends on the $4$-form dual magnetic fluxes (bi)linearly, as opposed to quadratically [ref] , as is clear from Eq. ([ref]).
Pancosmic Relativity and Nature's Hierarchies · Lg · 0.99
Cites it as support 10 papers
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This has three important consequences: * Individual pocket universes, including ours, can have very long lifetimes easily exceeding 10 Gyr [ref] . * When a bubble of new vacuum does form, it will be highly symmetric [ref] .
The Cosmological Constant Problem, Dark Energy, and the Landscape of String Theory · Connecting with Standard Cosmology · 0.96
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However, as emphasized in [ref] the actual value of the 4-form field strength in four dimensions (and not only its shift when crossing a membrane) satisfies Dirac quantization.
Relaxion Monodromy and the Weak Gravity Conjecture · Axion monodromy · 0.97
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So the cosmological constant does not always dominate, but just sometimes [ref] .
Hidden Variables of Gravity and Geometry and the Cosmological Constant Problem · Introduction · 0.96
Cites it as background 180 papers
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Under flux compactifications [ref] , an enormous number of different compactification possibilities are available [ref] , each leading to different 4-d laws of physics.
Fine-tuned vs. natural supersymmetry: what does the string landscape predict? · Introduction · 0.91
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Advances in String Theory over the last five years led to the discovery of the landscape of string theory [ref] .
Birth of the Universe from the Multiverse · String Landscape Multiverse · 0.95
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Consider multiverse theories (such as what one might expect from a string/M theory landscape [ref] ) in which the quantum state gives a superposition of different possible `constants' of physics.
Statistical Evidence Against Simple Forms of Wavefunction Collapse · Introduction · 0.94
Discussion
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