REVIEW
D = 5 maximally supersymmetric Yang-Mills theory diverges at six loops
High Energy Physics - Theory · Submitted 29 Oct 2012 · 63 references
Pith's verdict: A direct, multiply cross-checked numerical computation settles a real question — planar MSYM does diverge in D = 5 at six loops — and the exponential pattern is a secondary curiosity the authors themselves flag as possibly accidental.
T0 · AI review
Why Pith says this
Highlight any text to comment on it.
Referee report
The paper
The paper claims
Planar maximally supersymmetric Yang-Mills theory in five dimensions diverges at six loops, and the coefficient of that divergence is nonzero.
The reading
What carries the argument
Three pieces carry the argument. First, generalized unitarity builds the six-loop planar four-point integrand, organised over 68 cubic graphs with numerators fixed by dual conformal weight and by unitarity cuts, including a six-dimensional cut computed elsewhere that validates the result for $D ≤ 6$. Second, the ultraviolet divergence is extracted by Taylor-expanding each integrand in small external momenta, which turns the amplitude into a sum of six vacuum integrals with at most two doubled propagators, and then reduced further by consistency relations — shift-invariance identities of the integration measure, related to integration-by-parts identities but valid only for the leading $1/ε$ pole — down to the three-term combination above. Third, sector decomposition, as implemented in a modified version of FIESTA and integrated with the Vegas quasi-Monte Carlo, evaluates those integrals by splitting the Feynman-parameter space into roughly a million sectors, each with a single power-like singularity regularised by a change of measure.
Extended reading notes
Core claim
The paper's claim is that the first potential ultraviolet divergence of planar maximally supersymmetric Yang-Mills theory in $D = 5$ — the one that can first occur at six loops — has a nonzero coefficient, so the theory is perturbatively ultraviolet divergent in five dimensions. The six-loop four-point amplitude is reduced, by expanding in the external momenta and using integral consistency relations, to a three-term combination of scalar vacuum integrals, $10V^{(f)} + 5V^{(g)} - V^{(h)}$, and the numerical evaluation gives $A_4^{(6)}|_{{D=5},div} = -X (4π)^{15} (68.68 ± 0.17)/ε$ with $X = -s t u A_4^{tree}$. A secondary observation is that this value, together with the known two- through five-loop values $ρ_L$, is fit closely by a simple exponential form $ρ_L ≃ b_1 c_1^{L + a_1/L}$, which then predicts the approximate size of the divergences at seven loops and beyond in their own critical dimensions.
Load-bearing premise
The constructed six-loop integrand is the correct integrand of maximally supersymmetric Yang-Mills theory for loop momenta in five dimensions; this is supported by a large but not exhaustive set of unitarity cuts, only one of which is explicitly verified in six dimensions.
Editorial extensions
If this is right
- The finiteness bound $D < 4 + 6/L$ is saturated at $L = 6$: no additional hidden symmetry of planar maximally supersymmetric Yang-Mills theory suppresses the six-loop counterterm in $D = 5$.
- The link between five-dimensional maximally supersymmetric Yang-Mills theory and the six-dimensional $(2,0)$ theory cannot be used to argue for perturbative finiteness of the five-dimensional theory; any reconciliation must come from the ultraviolet completion cutting the divergence off with additional degrees of freedom.
- Through six loops the critical-dimension divergences follow an approximately exponential pattern in the loop order, which yields numerical predictions for $ρ_7$, $ρ_8$, $ρ_9$ of roughly $540$, $4490$, $38700$ (or $500$, $3650$, $26700$ under an alternative fit).
- Assuming the observed near-constancy of the ratio of $1/N_c^2$-suppressed to leading-colour divergences persists, the paper gives a prediction for the full colour-dressed six-loop divergence of the form $68.68 N_c^2 + 3100$ in the appropriate normalization.
- The same numerical pipeline — sector decomposition at six loops, roughly a million sectors on a 1000-node cluster in days — is argued to be within reach at seven loops, which is where the corresponding potential counterterm of $N = 8$ supergravity would first appear in $D = 4$.
Reading between the lines
- The exponential fit is presented as an observation without a mechanism; if it survives a seven-loop computation it would be the first hint that the critical-dimension divergences of this theory have a closed-form generating structure rather than being a sequence of unrelated numbers.
- Because the three-term basis $10V^{(f)} + 5V^{(g)} - V^{(h)}$ is not positive definite, the nonzero result rests entirely on the numerical evaluation rather than on a sign argument; an independent symbolic evaluation of that same combination by a different method would be a cleaner confirmation than any increase in Monte Carlo statistics.
- The obstruction found here for a five-dimensional gauge theory with a six-dimensional conformal completion is a useful template for the supergravity question: the same logic — saturation of the finiteness bound at the first allowed loop order — is exactly what a seven-loop $N = 8$ computation would test, and the paper's cost estimate makes that test look like an engineering problem rather than a c
- The paper's own framing leaves open whether the divergence is a genuine obstruction to the $(2,0)$ correspondence or an artefact of treating the five-dimensional theory as an ordinary perturbative quantum field theory; distinguishing those would require the $S$-dual extension of the five-dimensional amplitude that the authors propose as the next step.
Original abstract
The connection of maximally supersymmetric Yang-Mills theory to the (2,0) theory in six dimensions has raised the possibility that it might be perturbatively ultraviolet finite in five dimensions. We test this hypothesis by computing the coefficient of the first potential ultraviolet divergence of planar (large N_c) maximally supersymmetric Yang-Mills theory in D = 5, which occurs at six loops. We show that the coefficient is nonvanishing. Furthermore, the numerical value of the divergence falls very close to an approximate exponential formula based on the coefficients of the divergences through five loops. This formula predicts the approximate values of the ultraviolet divergence at loop orders L > 6 in the critical dimension D = 4 + 6/L. To obtain the six-loop divergence we first construct the planar six-loop four-point amplitude integrand using generalized unitarity. The ultraviolet divergence follows from a set of vacuum integrals, which are obtained by expanding the integrand in the external momenta. The vacuum integrals are integrated via sector decomposition, using a modified version of the FIESTA program.
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 connection of maximally supersymmetric Yang-Mills theory to the (2,0) theory in six dimensions has raised the possibility that it might be perturbatively ultraviolet finite in five dimensions. We test this hypothesis by computing the coefficient of the first potential ultraviolet divergence of planar (large N_c) maximally supersymmetric Yang-Mills theory in D = 5, which occurs at six loops. We show that the coefficient is nonvanishing. Furthermore, the numerical value of the divergence falls very close to an approximate exponential formula based on the coefficients of the divergences through five loops. This formula predicts the approximate values of the ultraviolet divergence at loop orders L > 6 in the critical dimension D = 4 + 6/L. To obtain the six-loop divergence we first construct the planar six-loop four-point amplitude integrand using generalized unitarity. The ultraviolet divergence follows from a set of vacuum integrals, which are obtained by expanding the integrand in the external momenta. The vacuum integrals are integrated via sector decomposition, using a modified version of the FIESTA program.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | The connection of maximally supersymmetric Yang-Mills theory to the (2,0) theory in six dimensions has raised the possibility that it might be perturbatively ultraviolet finite in five dimensions. | background 1.00 | 0.04 | 0.02 | speculative 0.57 |
| s1 | We test this hypothesis by computing the coefficient of the first potential ultraviolet divergence of planar (large N_c) maximally supersymmetric Yang-Mills theory in D = 5, which occurs at six loops. | contribution 0.96 | 0.93 | 0.07 | asserted 0.82 |
| s2 | We show that the coefficient is nonvanishing. | result 1.00 | 0.96 | 0.87 | asserted 1.00 |
| s3 | Furthermore, the numerical value of the divergence falls very close to an approximate exponential formula based on the coefficients of the divergences through five loops. | result 0.95 | 0.90 | 0.12 | asserted 0.96 |
| s4 | This formula predicts the approximate values of the ultraviolet divergence at loop orders L > 6 in the critical dimension D = 4 + 6/L. | interpretation 0.54 | 0.51 | 0.06 | asserted 0.89 |
| s5 | To obtain the six-loop divergence we first construct the planar six-loop four-point amplitude integrand using generalized unitarity. | method 0.99 | 0.95 | 0.02 | asserted 0.99 |
| s6 | The ultraviolet divergence follows from a set of vacuum integrals, which are obtained by expanding the integrand in the external momenta. | method 1.00 | 0.84 | 0.02 | asserted 1.00 |
| s7 | The vacuum integrals are integrated via sector decomposition, using a modified version of the FIESTA program. | method 1.00 | 0.85 | 0.02 | asserted 0.99 |
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:1210.7709 by the authors.
References
How the literature uses it
52 arXiv papers cite this in 66 sentences
Papers citing it · 49 sentences without a confident label
Builds on it 1 paper
-
This constitutes the first non-planar computation at six loops in $N=4$ SYM, thus extending the planar six-loops results [ref] .
Maximal Super-Yang-Mills at Six Loops via Novel Integrand Bootstrap · Introduction · 0.98
Uses its data or values 1 paper
-
The data are available up to 7 loops [ref] .
Positive Amplitudes In The Amplituhedron · Loop integrands · 0.92
Cites it as support 1 paper
-
This term is believed to be present in $_0^(5)$, since it is needed to absorb a six-loop divergence of the two-derivative Yang-Mills theory [ref] .
Higher Derivative Terms, Toroidal Compactification, and Weyl Anomalies in Six-Dimensional (2,0) Theories · The Yang-Mills Description at the Origin · 0.96
Cites it as background 13 papers
-
It was computed using unitarity to two loops in 1997 [ref] (see also [ref] ), to three loops in 2005 [ref] , to five loops in 2007—first at four loops [ref] , and five quickly thereafter [ref] —and to six loops around 2009 [ref] (although published later).
Amplitudes and Correlators to Ten Loops Using Simple, Graphical Bootstraps · Introduction · 0.86
-
In the last decade there has been considerable activity on the calculation of the amplitudes in maximally supersymmetric Yang-Mills theories (SYM) [ref] and maximally supersymmetric gravity [ref] .
Challenges of D=6 N=(1,1) SYM Theory · Introduction · 1.00
-
See for recent important attempts along this direction [ref] .
Instantonic string solitons on M5 branes · Introduction · 0.82
What it cites · 59 sentences without a confident label
Uses the method or tool of 12 papers
-
A long-standing challenge of numerically evaluating Euclidean Feynman integrals has been addressed by a computational technique called sector decomposition [ref] , implemented in several software packages [ref] including the FIESTA package [ref] , used here.
SecDec: A general program for sector decomposition · Introduction · 1.00
-
A long-standing challenge of numerically evaluating Euclidean Feynman integrals has been addressed by a computational technique called sector decomposition [ref] , implemented in several software packages [ref] including the FIESTA package [ref] , used here.
Resolution of singularities for multi-loop integrals · Introduction · 1.00
-
A long-standing challenge of numerically evaluating Euclidean Feynman integrals has been addressed by a computational technique called sector decomposition [ref] , implemented in several software packages [ref] including the FIESTA package [ref] , used here.
Feynman Integral Evaluation by a Sector decomposiTion Approach (FIESTA) · Introduction · 1.00
Uses data or values from 3 papers
-
[equation] The values of the divergences in $D=4+6/L$ from two through five loops have been given previously [ref] .
Manifest Ultraviolet Behavior for the Three-Loop Four-Point Amplitude of N=8 Supergravity · Extrapolating in loop order · 0.89
-
[equation] The values of the divergences in $D=4+6/L$ from two through five loops have been given previously [ref] .
Simplifying Multiloop Integrands and Ultraviolet Divergences of Gauge Theory and Gravity Amplitudes · Extrapolating in loop order · 0.89
-
[equation] The values of the divergences in $D=4+6/L$ from two through five loops have been given previously [ref] .
The Five-Loop Four-Point Amplitude of N=4 super-Yang-Mills Theory · Extrapolating in loop order · 0.89
Compares with 3 papers
-
[ref] (which is also known to agree with that in ref.
Constructing the correlation function of four stress-tensor multiplets and the four-particle amplitude in N=4 SYM · Constructing the integrand · 0.94
-
[ref] .) Our form for the integrand differs somewhat from recent ones based on four-dimensional constructions [ref] .
Basics of Generalized Unitarity · Constructing the integrand · 0.96
-
[ref] .) Our form for the integrand differs somewhat from recent ones based on four-dimensional constructions [ref] .
The Soft-Collinear Bootstrap: N=4 Yang-Mills Amplitudes at Six and Seven Loops · Constructing the integrand · 0.96
Cites as background 6 papers
-
[ref] .) The current consensus for $$ supergravity is that a $D=4$ potential counterterm valid under all known symmetries exists at seven loops [ref] .
The vanishing volume of D=4 superspace · Conclusions and outlook · 0.97
-
[ref] .) The current consensus for $$ supergravity is that a $D=4$ potential counterterm valid under all known symmetries exists at seven loops [ref] .
String theory dualities and supergravity divergences · Conclusions and outlook · 0.97
-
[ref] .) The current consensus for $$ supergravity is that a $D=4$ potential counterterm valid under all known symmetries exists at seven loops [ref] .
Progress on Ultraviolet Finiteness of Supergravity · Conclusions and outlook · 0.97
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.