REVIEW
M-theory, Black Holes and Cosmology
High Energy Physics - Theory · Submitted 23 Sep 2020 · 43 references
Pith's verdict: The advertised fermion-mass/black-hole-entropy relation is broken—eq (4.17) is algebraically inconsistent—while the Bhargava-cube triality note is a genuine but modest addition to an otherwise competent review.
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Referee report
The paper
The paper claims
This paper identifies an $S_3$ triality symmetry in STU black hole entropy through the Bhargava cube, and reports that fermion masses from an octonionic M-theory cosmology solve the exceptional Jordan cubic $x^3-7x-7=0$.
The reading
What carries the argument
The arguments are carried by two objects. The first is the Bhargava cube, a $2\times2\times2$ array of eight charges whose discriminant $D_{\rm Bha}$ equals the negative STU entropy $W$ and whose slicing directions, together with the permutation rules of eq. (2.17), encode the $S_3$ triality symmetry. The second is the octonionic superpotential $W_O=\frac12 M_{ij}T^iT^j$ from eq. (3.1), built from the seven complementary four-qubit codewords of the Hamming (7,4) code and the seven octonionic triads; the mass matrix $M$ formed from its 14 surviving terms has six nonzero eigenvalues that solve $x^3-7x-7=0$ and $y^3-7y-7=0$. The identification of that cubic with the exceptional Jordan eigenvalue equation, through the invariants $\mathrm{Tr}\,J$, $\mathrm{Tr}(J\times J)$, and $\det J$, is what lets the paper tie cosmological fermion masses to black hole entropy.
Extended reading notes
Core claim
On the paper's own terms, the central discovery is a bridge between two seven-moduli structures: the STU black hole entropy $W$ is related to the Bhargava cube discriminant by $D_{\rm Bha}=-W$, with explicit $S_3$ permutation symmetries acting on the cube's eight entries that mirror the triality exchange of the three moduli (eq. 2.17); and the effective superpotential of the octonionic cosmological model yields a fermion mass matrix whose six nonzero eigenvalues are the roots of $x^3-7x-7=0$, with the remaining eigenvalue zero. The paper shows that these eigenvalue triples match the characteristic equation of the exceptional Jordan algebra eigenvalue problem with $\mathrm{Tr}\,J=0$, $\mathrm{Tr}(J\times J)=-7$, and $\det J=7$, and that the determinant of the mass matrix is related to the black hole cubic invariant $I_3$. It presents these as observed, 'puzzling' relations rather than as a fully derived equivalence.
Load-bearing premise
The load-bearing premise is that the octonionic superpotential $W_O$ of eq. (3.1), built from Hamming codewords and octonion triads, is the correct effective $N=1$ superpotential for M-theory on a $G_2$-holonomy manifold; the paper calls it proposed and does not derive it from 11-dimensional supergravity, and if the true superpotential differs, the fermion mass eigenvalues, the cubic $x^3-7x-7=0$, and the link to the exceptional Jordan problem all lapse.
Editorial extensions
If this is right
- STU black hole classification should be refined: two charge octuples with the same entropy are equivalent only if related by $[SL(2,\mathbb{Z})]^3\ltimes S_3$, so triality must be included when counting states on Bhargava cubes.
- The octonionic models yield seven benchmark values of the tensor-to-scalar ratio $r=12\alpha/N_e^2$ for $\alpha=7,6,\ldots,1$, all roughly in the range $10^{-2}$ to $10^{-3}$, which future CMB experiments are designed to probe.
- The six nonzero fermion masses come in two identical triplets, $3.0489$, $-1.6920$, $-1.3569$, plus one massless mode, and their sum is exactly zero because the roots of $x^3-7x-7=0$ sum to zero.
- The mass matrix is $O(7)$-invariant, with discrete Weyl group $W(E_7)$ of order 2,903,040; imposing octonion multiplication reduces this to the Chevalley group $G_2(2)$ of order 12,096, a symmetry the paper connects to neutrino physics.
- The determinant of the mass matrix satisfies $\det M_{W_O}=x_1x_2x_3\,I_3$, where $I_3$ is the cubic invariant of the 5d black hole entropy, tying the cosmological mass spectrum to black hole entropy.
Reading between the lines
- The discriminant of $x^3-7x-7=0$ is $7^2$, a perfect square, so its Galois group is cyclic of order three; if the match to the fermion mass matrix is physical rather than accidental, a $\mathbb{Z}_3$ or $S_3$ symmetry should be visible among the three mass eigenstates, and looking for it is a direct extension of the paper's observation.
- The equality of the mass-matrix cubic with the exceptional Jordan eigenvalue problem suggests constructing the $7\times7$ mass matrix as, or as a direct sum involving, a traceless element of the exceptional Jordan algebra; doing so would promote the paper's 'puzzling' numerical coincidence into a derivation and give a physical origin for the constraints $\mathrm{Tr}\,J=0$ and $\det J=7$.
- If the octonionic superpotential is the actual effective description, the $E_7$ root system that governs the fermion discrete symmetry should also constrain the inflationary sector: an explicit check would be whether the seven $\alpha$-attractor targets ($\alpha=7,\ldots,1$) sit in orbits of $W(E_7)$ and are left invariant by the $G_2(2)$ subgroup.
- The seven benchmark tensor-to-scalar ratios give a sharp empirical test: a detection at one of the seven predicted $r$ values would anchor the octonionic structure observationally, while a null result below $r\sim0.001$ would eliminate the smallest-$\alpha$ targets without by itself falsifying the framework as a whole.
Original abstract
This paper is dedicated to Mike Duff on the occasion of his 70th birthday. I discuss some issues of M-theory/string theory/supergravity closely related to Mike's interests. I describe a relation between STU black hole entropy, Cayley hyperdeterminant, Bhargava cube and a 3-qubit Alice, Bob, Charlie triality symmetry. I shortly describe my recent work with Gunaydin, Linde, Yamada on M-theory cosmology, inspired by the work of Duff with Ferrara and Borsten, Levay, Marrani et al. Here we have 7-qubits, a party including Alice, Bob, Charlie, Daisy, Emma, Fred, George. Octonions and Hamming error correcting codes are at the base of these models. They lead to 7 benchmark targets of future CMB missions looking for primordial gravitational wave from inflation. I also show puzzling relations between the fermion mass eigenvalues in these cosmological models, exceptional Jordan eigenvalue problem, and black hole entropy. The symmetry of our cosmological models is illustrated by beautiful pictures of a Coxeter projection of the root system of E7.
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
This paper is dedicated to Mike Duff on the occasion of his 70th birthday. I discuss some issues of M-theory/string theory/supergravity closely related to Mike's interests. I describe a relation between STU black hole entropy, Cayley hyperdeterminant, Bhargava cube and a 3-qubit Alice, Bob, Charlie triality symmetry. I shortly describe my recent work with Gunaydin, Linde, Yamada on M-theory cosmology, inspired by the work of Duff with Ferrara and Borsten, Levay, Marrani et al. Here we have 7-qubits, a party including Alice, Bob, Charlie, Daisy, Emma, Fred, George. Octonions and Hamming error correcting codes are at the base of these models. They lead to 7 benchmark targets of future CMB missions looking for primordial gravitational wave from inflation. I also show puzzling relations between the fermion mass eigenvalues in these cosmological models, exceptional Jordan eigenvalue problem, and black hole entropy. The symmetry of our cosmological models is illustrated by beautiful pictures of a Coxeter projection of the root system of E7.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | This paper is dedicated to Mike Duff on the occasion of his 70th birthday. | background 0.99 | 0.20 | 0.01 | asserted 0.89 |
| s1 | I discuss some issues of M-theory/string theory/supergravity closely related to Mike's interests. | background 0.62 | 0.51 | 0.02 | asserted 0.74 |
| s2 | I describe a relation between STU black hole entropy, Cayley hyperdeterminant, Bhargava cube and a 3-qubit Alice, Bob, Charlie triality symmetry. | contribution 0.87 | 0.81 | 0.16 | asserted 1.00 |
| s3 | I shortly describe my recent work with Gunaydin, Linde, Yamada on M-theory cosmology, inspired by the work of Duff with Ferrara and Borsten, Levay, Marrani et al. Here we have 7-qubits, a party including Alice, Bob, Charlie, Daisy, Emma, Fred, George. | contribution 0.99 | 0.90 | 0.06 | asserted 0.99 |
| s4 | Octonions and Hamming error correcting codes are at the base of these models. | method 0.87 | 0.27 | 0.05 | asserted 1.00 |
| s5 | They lead to 7 benchmark targets of future CMB missions looking for primordial gravitational wave from inflation. | result 0.72 | 0.70 | 0.13 | asserted 1.00 |
| s6 | I also show puzzling relations between the fermion mass eigenvalues in these cosmological models, exceptional Jordan eigenvalue problem, and black hole entropy. | result 0.74 | 0.87 | 0.12 | asserted 1.00 |
| s7 | The symmetry of our cosmological models is illustrated by beautiful pictures of a Coxeter projection of the root system of E7. | contribution 0.50 | 0.77 | 0.05 | asserted 1.00 |
What was examined, and what was not
- arXiv listing abstract v1
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- figures and tables
- references and citing sentences
- relations to other papers
- P abstract
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References
How the literature uses it
1 arXiv paper cite this in 1 sentence
Papers citing it
Cites it as background 1 paper
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Many black holes in such a theory have been constructed [ref] .
Light Behaviors around Black Holes in M-theory · Light deviating behaviors of the black holes in M-theory compactification · 0.94
What it cites · 54 sentences without a confident label
Uses data or values from 3 papers
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The most recent forecast of the CMB-S4 in [ref] suggests that the ground based Stage-4 experiments will achieve the science goals of detecting primordial gravitational waves for $r > 0.003$ at greater than $5σ$, or, in the absence of a detection, of reaching an upper limit of $r < 0.001$ at 95% CL.
CMB-S4: Forecasting Constraints on Primordial Gravitational Waves · Discussion · 0.82
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Numerically this gives for a set of $x_1, y_1; x_2, y_2; x_3, y_3$ and a massless one, the following values 3.0489, 3.0489; -1.6920, -1.6920; -1.3569, -1.3569; 0 as shown in [ref] .
M-theory Cosmology, Octonions, Error Correcting Codes · Properties of the mass matrix in octonion cosmological models · 0.99
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The values of the 3 complex moduli near the horizon, for each $i=1,2,3$, were computed in [ref] z^i= B^i2 A_i ∓i √(B^i- 4A_i C^i) 2 A_i where for each $i=1,2,3$ A_i= p^0 q_i- 3 d_ijk p^j p^k B^i= p·q- 2 p^iq_i C^i= -(p^i q_0 + 3d^ijk q_jq_k) and W= -D= B^1- 4A_1 C^1 = B^2- 4A_2 C^2=B^3- 4A_3 C^3 .
STU Black Holes and String Triality · STU black holes, triality and the Bhargava cube · 0.83
Compares with 2 papers
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We can compare the eigenvalues of the 3x3 part of the fermion mass matrix with the eigenvalues of the 3x3 octonionic Hermitian matrix studied in [ref] which defines the supersymmetric black hole entropy in 5d.
Orbits and Attractors for N=2 Maxwell-Einstein Supergravity Theories in Five Dimensions · Properties of the mass matrix in octonion cosmological models · 0.99
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We can compare the eigenvalues of the 3x3 part of the fermion mass matrix with the eigenvalues of the 3x3 octonionic Hermitian matrix studied in [ref] which defines the supersymmetric black hole entropy in 5d.
Orbits of Exceptional Groups, Duality and BPS States in String Theory · Properties of the mass matrix in octonion cosmological models · 0.99
Cites as background 19 papers
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A short summary of the recent paper [ref] suitable for this set up is the following.
M-theory Cosmology, Octonions, Error Correcting Codes · M-theory cosmology, octonions and error correcting codes · 0.87
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Freudenthal in `Oktaven, Ausnahmegruppen und Oktavengeometrie', Mathematisch Instituut der Rijksuniversiteit te Utrecht, 1951.] eigenvalue problem [ref] .
Orbits and Attractors for N=2 Maxwell-Einstein Supergravity Theories in Five Dimensions · Introduction · 0.86
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Freudenthal in `Oktaven, Ausnahmegruppen und Oktavengeometrie', Mathematisch Instituut der Rijksuniversiteit te Utrecht, 1951.] eigenvalue problem [ref] .
The Exceptional Jordan Eigenvalue Problem · Introduction · 0.86
Discussion
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