REVIEW
Quantum Horizons of the Standard Model Landscape
High Energy Physics - Theory · Submitted 8 Mar 2007 · 16 references
Pith's verdict: A genuinely new landscape inside the Standard Model itself, with a clean 3D quantum-horizon construction and a 4D black-string argument that is asserted rather than proved.
T0 · AI review
Why Pith says this
Highlight any text to comment on it.
Referee report
The paper
The paper claims
The Standard Model, compactified on a 20-micron circle, has a landscape of lower-dimensional vacua whose horizons are quantum objects.
The reading
What carries the argument
The machinery is a reduction of the Einstein equations to a one-dimensional mechanical problem. For a metric of the form $ds^2 = -A^2(z)dt^2 + dz^2 + R^2(z)dφ^2$ with an energy-momentum tensor of perfect-fluid type, the ratio of the $tt$ and $zz$ equations forces $A = R'$, and the remaining equation becomes $R'' = -dU/dR$ with $dU/dR = M_3^{-1} R ρ(R)$, where $ρ(R)$ is the Casimir energy density. Rewriting the metric as $ds^2 = -f(R)dt^2 + f(R)^{-1}dR^2 + R^2 dφ^2$ with $f = ε - U(R)$ turns the problem into a familiar black-hole form: the compactified vacuum sits at an extremum of $U$, the interpolating solution is the critical trajectory that reaches the top of $U$ in infinite affine time, and non-extremal solutions are those that undershoot and turn at a zero of $f$. The same construction, with a friction term generated by the warp factor, carries over to the four-dimensional black string.
Extended reading notes
Core claim
The central claim is that the Standard Model plus general relativity has a genuine landscape of lower-dimensional vacua, and that these vacua are realized geometrically as the near-horizon regions of quantum extremal black objects. The vacuum is found by balancing the four-dimensional cosmological constant against Casimir energy on a circle; the Casimir potential is dominated at any radius by the lightest states, and with Majorana neutrinos the fermionic degrees of freedom are few enough and light enough that a minimum forms at $R_0$ of order $1/m_ν$, giving $AdS_3$ times $S^1$ with circumference roughly 20 microns. Because the only would-be mass term for the photon's Wilson loop comes from the electron and is suppressed by $e^{-m_e/m_ν}$, the vacuum is not unique but a continuum labelled by the Wilson loop. The second claim is that one can interpolate from four-dimensional Minkowski space to this vacuum with a cosmic-string-like geometry whose near-horizon limit is the $AdS_3$ times $S^1$ throat, and similarly from three to two dimensions with a black hole whose horizon is held up entirely by the Casimir energy. Such horizons are impossible classically, since no-hair arguments follow from the null energy condition, and the authors emphasize that the Casimir energy violates it. The extremal three-dimensional black holes are the sharpest case: their entropy depends only on the conical deficit angle, not on $G_N$ or $ℏ$, so it survives a decoupling limit in which gravity is switched off and the geometry becomes a cone.
Load-bearing premise
The interpolating geometries are built by treating the Casimir energy-momentum tensor in the spatially varying circle as if it were locally the flat-space perfect fluid of a constant-radius circle, dropping all derivative corrections; the paper states in Section 4.1 that the derivative part can be safely ignored, and if that fails near the throat the horizons would not exist as constructed.
Editorial extensions
If this is right
- There exists a two-dimensional conformal field theory with central charge of order $10^{90}$ dual to a background containing the Standard Model, whose operator spectrum has a few $O(1)$-dimension operators, a nearly marginal Wilson-loop operator with anomalous dimension of order $e^{-10^{8}}$, and then a gap of order $10^{30}$ to neutrino and Kaluza-Klein operators.
- The extremal three-dimensional quantum black holes have entropy $S = L/(4G_3)$ set by the opening angle of a cone, finite as $G_N \to 0$, which opens the possibility of a microscopic counting of that entropy without gravity, analogous to the BPS decoupling limit.
- Quantum black holes without the $Z_2$ flux evaporate until the horizon reaches the Planck scale, while those carrying the flux stop at a critical opening angle and settle into the extremal interpolating solution.
- The authors conjecture that the wider landscape of $AdS$ vacua in string theory can likewise be exhibited as near-horizon geometries of exotic extremal black branes, with orientifold planes or other negative-energy sources playing the role that Casimir energy plays here.
Reading between the lines
- If the local flat-space approximation to the Casimir stress tensor holds, the same construction should apply to any non-supersymmetric theory with a fine-tuned cosmological constant and a light fermion spectrum, which makes the mechanism a generic route from a unique vacuum to a discretum rather than a peculiarity of the Standard Model.
- The claim that the dual CFT must be ill-defined at a non-perturbative level, because the four-dimensional de Sitter vacuum decays, is a testable structural statement: a CFT with a marginal coupling whose potential is unbounded below would be the boundary signature of a bulk instability that is otherwise hidden from a small observer.
- The Wilson-loop direction being exponentially flat suggests an observational handle: if the vacuum were ever entered, the value of the Wilson loop would be frozen by cosmology rather than by energetics, so it would carry a memory of the formation history rather than relaxing to a preferred value.
Original abstract
The long-distance effective field theory of our Universe--the Standard Model coupled to gravity--has a unique 4D vacuum, but we show that it also has a landscape of lower-dimensional vacua, with the potential for moduli arising from vacuum and Casimir energies. For minimal Majorana neutrino masses, we find a near-continuous infinity of AdS3xS1 vacua, with circumference ~20 microns and AdS3 length 4x10^25 m. By AdS/CFT, there is a CFT2 of central charge c~10^90 which contains the Standard Model (and beyond) coupled to quantum gravity in this vacuum. Physics in these vacua is the same as in ours for energies between 10^-1 eV and 10^48 GeV, so this CFT2 also describes all the physics of our vacuum in this energy range. We show that it is possible to realize quantum-stabilized AdS vacua as near-horizon regions of new kinds of quantum extremal black objects in the higher-dimensional space--near critical black strings in 4D, near-critical black holes in 3D. The violation of the null-energy condition by the Casimir energy is crucial for these horizons to exist, as has already been realized for analogous non-extremal 3D black holes by Emparan, Fabbri and Kaloper. The new extremal 3D black holes are particularly interesting--they are (meta)stable with an entropy independent of hbar and G_N, so a microscopic counting of the entropy may be possible in the G_N->0 limit. Our results suggest that it should be possible to realize the larger landscape of AdS vacua in string theory as near-horizon geometries of new extremal black brane solutions.
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
The long-distance effective field theory of our Universe--the Standard Model coupled to gravity--has a unique 4D vacuum, but we show that it also has a landscape of lower-dimensional vacua, with the potential for moduli arising from vacuum and Casimir energies. For minimal Majorana neutrino masses, we find a near-continuous infinity of AdS3xS1 vacua, with circumference ~20 microns and AdS3 length 4x10^25 m. By AdS/CFT, there is a CFT2 of central charge c~10^90 which contains the Standard Model (and beyond) coupled to quantum gravity in this vacuum. Physics in these vacua is the same as in ours for energies between 10^-1 eV and 10^48 GeV, so this CFT2 also describes all the physics of our vacuum in this energy range. We show that it is possible to realize quantum-stabilized AdS vacua as near-horizon regions of new kinds of quantum extremal black objects in the higher-dimensional space--near critical black strings in 4D, near-critical black holes in 3D. The violation of the null-energy condition by the Casimir energy is crucial for these horizons to exist, as has already been realized for analogous non-extremal 3D black holes by Emparan, Fabbri and Kaloper. The new extremal 3D black holes are particularly interesting--they are (meta)stable with an entropy independent of hbar and G_N, so a microscopic counting of the entropy may be possible in the G_N->0 limit. Our results suggest that it should be possible to realize the larger landscape of AdS vacua in string theory as near-horizon geometries of new extremal black brane solutions.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | The long-distance effective field theory of our Universe--the Standard Model coupled to gravity--has a unique 4D vacuum, but we show that it also has a landscape of lower-dimensional vacua, with the potential for moduli arising from vacuum and Casimir energies. | result 0.58 | 0.83 | 0.61 | asserted 0.91 |
| s1 | For minimal Majorana neutrino masses, we find a near-continuous infinity of AdS3xS1 vacua, with circumference ~20 microns and AdS3 length 4x10^25 m. | result 1.00 | 0.94 | 0.22 | asserted 1.00 |
| s2 | By AdS/CFT, there is a CFT2 of central charge c~10^90 which contains the Standard Model (and beyond) coupled to quantum gravity in this vacuum. | result 0.69 | 0.70 | 0.16 | asserted 1.00 |
| s3 | Physics in these vacua is the same as in ours for energies between 10^-1 eV and 10^48 GeV, so this CFT2 also describes all the physics of our vacuum in this energy range. | interpretation 0.66 | 0.76 | 0.17 | asserted 1.00 |
| s4 | We show that it is possible to realize quantum-stabilized AdS vacua as near-horizon regions of new kinds of quantum extremal black objects in the higher-dimensional space--near critical black strings in 4D, near-critical black holes in 3D. | result 0.69 | 0.91 | 0.20 | asserted 0.56 |
| s5 | The violation of the null-energy condition by the Casimir energy is crucial for these horizons to exist, as has already been realized for analogous non-extremal 3D black holes by Emparan, Fabbri and Kaloper. | background 0.58 | 0.15 | 0.05 | asserted 1.00 |
| s6 | The new extremal 3D black holes are particularly interesting--they are (meta)stable with an entropy independent of hbar and G_N, so a microscopic counting of the entropy may be possible in the G_N->0 limit. | result 0.48 | 0.68 | 0.08 | hedged possibility 0.81 |
| s7 | Our results suggest that it should be possible to realize the larger landscape of AdS vacua in string theory as near-horizon geometries of new extremal black brane solutions. | interpretation 0.82 | 0.41 | 0.34 | hedged possibility 1.00 |
What was examined, and what was not
- arXiv listing abstract v1
- 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/0703067 by the authors.
References
How later papers used it
64 later papers cite it
3 later papers by other authors are listed below: 2 built on it and 1 used its method or tool.
Builds on it 2 of 3 papers with this label
-
Extended this paper's results and explored the stabilization of compact dimensions at finite temperature.
Finite Temperature Structure of the Compactified Standard Model (2011) · 1.00 · paraphrased: the licence does not allow quoting
-
Extended this paper by explicitly finding new vacua for toroidal and spherical compactifications of the standard model.
Standard Model Vacua for Two-dimensional Compactifications (2010) · 0.87 · paraphrased: the licence does not allow quoting
Uses its method or tool 1 of 4 papers with this label
-
Adopted the same parametrization as this paper.
Standard model with compactified spatial dimensions (2011) · 0.97 · paraphrased: the licence does not allow quoting
How the literature uses it
61 arXiv papers cite this in 114 sentences
Papers citing it · 89 sentences without a confident label
Builds on it 3 papers
-
In this paper we extend the results of [ref] and [ref] and explore the stabilization of compact dimensions at finite temperature.
Finite Temperature Structure of the Compactified Standard Model · Introduction · 1.00
-
This work completes the series of papers [ref] concerning lower-dimensional standard model vacua by considering the last remaining case, when all spatial dimensions are compactified.
Standard model with compactified spatial dimensions · Introduction · 1.00
-
The basic formalism used in this paper was developed in [ref] and this work extends [ref] by explicitly finding new vacua for toroidal and spherical compactifications of the standard model.
Standard Model Vacua for Two-dimensional Compactifications · Introduction · 0.87
Uses its method or tool 4 papers
-
We adopt the same parametrization as in [ref] ,
Standard model with compactified spatial dimensions · Compactification on a 3-torus at zero temperature · 0.97
-
Those conditions are [equation] Their derivation is given in [ref] .
Standard Model Vacua for Two-dimensional Compactifications · Compactification on a 2D torus · 0.85
-
We will follow [ref] and think of the potential as the Casimir energy density of the higher-dimensional theory integrated over the internal space, [equation] This energy density can be extracted from the stress-energy tensor's vacuum expectation value, [equation] which, since this theory is free, can be related to the two-point function $G(x - x') = ⟨Φ(x) Φ̅(x')⟩$ on $ℝ^1,d ×S^1$, [equation] In turn, this two-point function can be constructed by imaging the two-point function[Since we will only evaluate this two-point function at spatial separations, we will not need its form inside the light-cone.] in higher-dimensional flat space $ℝ^1, d+1$, [equation] around the compact space with an appropriate phase, [equation] We exclude the $n = 0$ contribution since it will only renormalize the cosmological constant and will not affect the potential's $θ$-dependence.
Instanton Expansions and Phase Transitions · From the Casimir Energy · 0.95
Compares with it 3 papers
-
Those points match the ones found along the lines of [ref] .
Finite Temperature Structure of the Compactified Standard Model · One-dimensional compactification · 0.96
-
[equation] The $0$-th order expressions, which may be interpreted as the Casimir energy/pressures, match known results for the time-independent case [ref] .
Stress-Energy Tensor of a Scalar Field on a Product Spacetime with a Time-Dependent Compact Dimension · Scenario · 0.99
-
The Casimir source as the crucial negative contribution in the potential is quantum, similarly to [ref] , but perturbative, with explicitly known stress energy contributions to the equations of motion (as in other backgrounds such as [ref] ).
Hyperbolic compactification of M-theory and de Sitter quantum gravity · Context and further directions · 0.97
Cites it as support 3 papers
-
This issue was considered in e.g. [ref] , with the conclusion that non-perturbative effects are also similarly exponentially suppressed.
Small Vacuum Energy from Small Equivalence Violation in Scalar Gravity · Aharanov-Bohm potential · 0.96
-
in general we know we have at least 3 dims, some of which may have been small in the past there are probably at least as many vacua with more dimensions compactified as there are 3-dimensional ones in fact even SM has a "landscape" of lower dimensional vacua [ref]
Observing the Dimensionality of Our Parent Vacuum · Introduction and Summary · 0.98
-
There is even theoretical support for this [For example, Refs. [ref] show that the SM with only $3$ Majorana neutrinos does satisfy the sharpened version of the weak gravity conjecture by Ooguri and Vafa [ref] , presumably implying that such SM cannot be consistently embedded into a quantum theory of gravity.].
One-loop running of dimension-six Higgs-neutrino operators and implications of a large neutrino dipole moment · Introduction · 0.98
Cites it as background 11 papers
-
A discussion of the nature of this effect would take us too far afield here, but we may mention that the Casimir effect arises naturally in spaces with toral topology; see [ref] for a general discussion of Casimir effects in cosmology, and [ref] [ref] for recent discussions from a string-theoretic point of view.
The Arrow Of Time In The Landscape · Section · 0.89
-
Popular choices are orientifolds or higher-derivative effects [ref] , but here we will choose Casimir energies [ref] , which we will now review; a good source is [ref] , or the textbook [ref] .
An M-theory dS maximum from Casimir energies on Riemann-flat manifolds · Warm-up: A dS7 from M-theory on T4 · 0.93
-
The basis of this framework is the large extra dimension model [ref] .
Extra dimensions with light and heavy neutral leptons: An application to CE$\nu$NS · Summary and Future Outlook · 0.91
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.