REVIEW
The IR/UV Connection in the Non-Commutative Gauge Theories
High Energy Physics - Theory · Submitted 9 Feb 2000 · 9 references
Pith's verdict: The gauge-theory half of the IR/UV story, and it holds up: the 1/theta^2 and 1/theta poles with coefficient (Ns + 2 − 2Nf) are computed explicitly and have survived twenty-five years of rederivation.
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Referee report
The paper
The paper claims
In noncommutative gauge theory, high-momentum loops leave poles at low momentum, so the limit of vanishing noncommutativity is singular.
The reading
What carries the argument
The load-bearing mechanism is the phase factor $e^{i p theta l}$ attached to each non-planar diagram, which at large loop momentum $l$ oscillates and renders finite an integral that would be divergent in the commutative theory, but which becomes ineffective as the external noncommutative momentum $tilde p = theta p$ goes to zero. The computation is carried by the Fourier transform identity $int d^4 l / (2pi)^4, l^{-4} e^{i tilde p l} = i alpha (log Lambda - log |tilde p|)$ and its descendants obtained by differentiating with respect to $tilde p$, which convert the regulated short-distance behaviour into explicit $log |tilde p|$ and hence into poles in $tilde p$; the resulting tensor structures $tilde p^mu tilde p^nu / tilde p^4$ and $tilde p^{mu_1} tilde p^{mu_2} tilde p^{mu_3} / tilde p^4$ are automatically transverse in the sense of the Ward identity, which is what makes the anomalous terms compatible with gauge invariance despite breaking Lorentz invariance.
Extended reading notes
Core claim
The paper's central claim is that one-loop non-planar diagrams in noncommutative gauge theory generate infrared singularities that scale as inverse powers of the noncommutativity parameter, contradicting the expectation that a theory whose worst commutative divergences are logarithmic should produce at most logarithmic anomalous $tilde p$ dependence. Concretely, the photon vacuum polarization in noncommutative $U(1)$ Yang-Mills contains a term $iPi^{mu nu}(p) = 8 i g^2 (N_s + 2 - 2N_f) alpha, tilde p^mu tilde p^nu / tilde p^4$, which is transverse (since $p cdot tilde p = 0$) but splits the dispersion relation of the two physical photon polarizations: the mode polarized perpendicular to $tilde P$ keeps $p_0^2 = p_3^2 + P^2$, while the mode polarized along $tilde P$ obeys $p_0^2 = p_3^2 + P^2 + c g^2 / (theta^2 P^2)$. The three-photon vertex carries a weaker but still non-analytic pole, $Gamma^{mu_1 mu_2 mu_3} = -8 alpha g^3 (N_s + 2 - 2N_f) cos(tfrac{1}{2} tilde p_3 p_1) sum_i tilde p_i^{mu_1} tilde p_i^{mu_2} tilde p_i^{mu_3} / tilde p_i^4$ plus terms at most logarithmic. Because the coefficient counts bosons minus fermions, all inverse-power poles disappear in supersymmetric models, and the authors argue that noncommutative super Yang-Mills with 16 real supercharges is free of the anomalous effects altogether, being the one known example that reduces to its commutative counterpart as $theta to 0$.
Load-bearing premise
The claim that the anomalous terms respect gauge invariance rests on a check in Section 5 that covers only two kinematic corners of one process, gauge bosons plus fermions scattering to gauge bosons plus fermions, and the authors themselves acknowledge that the scalar version of this check is deferred to a companion paper listed as in preparation.
Editorial extensions
If this is right
- The commutative limit of a noncommutative gauge theory is not smooth: physical quantities such as the photon dispersion relation diverge as $theta to 0$, so noncommutativity cannot be treated as a small perturbation of ordinary Yang-Mills theory.
- The two photon polarizations acquire different dispersion relations, a Lorentz-violating splitting that survives because $theta$ itself picks out a preferred plane; the effect is local in the directions orthogonal to that plane and nonlocal within it.
- Inverse-power poles cancel between bosons and fermions at one loop, so any supersymmetric noncommutative gauge theory has at worst logarithmic anomalous dependence on $tilde p$, tied to the coefficient of the commutative beta function.
- Noncommutative super Yang-Mills with 16 real supercharges appears to be completely free of these anomalies, making it the natural candidate for a theory with a well-behaved $theta to 0$ limit.
- A theory with more fermions than bosons gets a negative coefficient, which the authors note destabilizes the low-energy theory, paralleling the behaviour of $phi^4$ with Yukawa-coupled fermions.
Reading between the lines
- If the inverse-power poles are real, $theta$ is not a continuously deformable parameter of the quantum theory but a phase-labeling one: the noncommutative and commutative theories would sit in different phases, which suggests treating noncommutativity as fundamental rather than as a small correction to be expanded in.
- The cancellation condition $N_s + 2 - 2N_f = 0$ looks like a one-loop coefficient of its own, distinct from the ordinary beta function; it would be worth asking whether this same combination controls the subleading logarithmic terms, which would make the pole coefficient a genuine one-loop invariant of the noncommutative theory.
- Because the anomalous terms are transverse yet Lorentz-violating, the polarization splitting is the cleanest observable signature: in any setting where $theta$ arises as a background field, the two photon polarizations propagate with measurably different velocities at low momentum.
- The authors' gauge-invariance check covers only two kinematic corners of a single scattering process; the natural extension is a full all-kinematics Ward identity check, and separately the scalar version they defer, since scalar loops enter with their own cubic and quartic vertices.
Original abstract
Quantum field theory on non-commutative spaces does not enjoy the usual ultraviolet-infrared decoupling that forms the basis for conventional renormalization. The high momentum contributions to loop integrations can lead to unfamiliar long distance behavior which can potentially undermine naive expectations for the IR behavior of the theory. These "anomalies" involve non-analytic behavior in the noncommutativity parameter Theta making the limit Theta goes to zero singular. In this paper we will analyze such effects in the one loop approximation to gauge theories on non-commutative space. We will see that contrary to expectations poles in Theta do occur and lead to large discrepancies between the expected and actual infrared behavior. We find that poles in Theta are absent in supersymmetric theories. The "anomalies" are generally still present, but only at the logarithmic level. A notable exception is non-commutative super Yang Mills theory with 16 real supercharges in which anomalous effects seem to be absent altogether.
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
Quantum field theory on non-commutative spaces does not enjoy the usual ultraviolet-infrared decoupling that forms the basis for conventional renormalization. The high momentum contributions to loop integrations can lead to unfamiliar long distance behavior which can potentially undermine naive expectations for the IR behavior of the theory. These "anomalies" involve non-analytic behavior in the noncommutativity parameter Theta making the limit Theta goes to zero singular. In this paper we will analyze such effects in the one loop approximation to gauge theories on non-commutative space. We will see that contrary to expectations poles in Theta do occur and lead to large discrepancies between the expected and actual infrared behavior. We find that poles in Theta are absent in supersymmetric theories. The "anomalies" are generally still present, but only at the logarithmic level. A notable exception is non-commutative super Yang Mills theory with 16 real supercharges in which anomalous effects seem to be absent altogether.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | Quantum field theory on non-commutative spaces does not enjoy the usual ultraviolet-infrared decoupling that forms the basis for conventional renormalization. | background 1.00 | 0.05 | 0.05 | asserted 1.00 |
| s1 | The high momentum contributions to loop integrations can lead to unfamiliar long distance behavior which can potentially undermine naive expectations for the IR behavior of the theory. | background 1.00 | 0.06 | 0.04 | hedged possibility 0.95 |
| s2 | These "anomalies" involve non-analytic behavior in the noncommutativity parameter Theta making the limit Theta goes to zero singular. | background 0.96 | 0.10 | 0.07 | asserted 1.00 |
| s3 | In this paper we will analyze such effects in the one loop approximation to gauge theories on non-commutative space. | contribution 0.95 | 0.55 | 0.04 | asserted 0.81 |
| s4 | We will see that contrary to expectations poles in Theta do occur and lead to large discrepancies between the expected and actual infrared behavior. | result 0.98 | 0.80 | 0.44 | asserted 0.99 |
| s5 | We find that poles in Theta are absent in supersymmetric theories. | result 1.00 | 0.83 | 0.20 | asserted 1.00 |
| s6 | The "anomalies" are generally still present, but only at the logarithmic level. | result 0.99 | 0.77 | 0.14 | asserted 0.97 |
| s7 | A notable exception is non-commutative super Yang Mills theory with 16 real supercharges in which anomalous effects seem to be absent altogether. | result 1.00 | 0.58 | 0.15 | hedged possibility 0.94 |
What was examined, and what was not
- arXiv listing abstract v2
- full text
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- relations to other papers
- P abstract
- S sections
- T body sentences
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- R cross-paper relations
Figures
Figures reproduced from arXiv:hep-th/0002075 by the authors.
References
How the literature uses it
77 arXiv papers cite this in 123 sentences
Papers citing it · 93 sentences without a confident label
Compares with it 3 papers
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However, in the limit $→0$ transverality is recovered, and [ref] reduces to the well-known expression [ref] [equation] In the ultraviolet, the graphs of fig:1loop_3A_all diverge only logarithmically.
Loop Calculations for the Non-Commutative U(1) Gauge Field Model with Oscillator Term · Vertex corrections at one-loop level · 0.86
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These results are in agreement with the literature [ref] .
Slavnov-Taylor identities, non-commutative gauge theories and infrared divergences · Only external $U(1)$ legs · 0.90
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This is reminiscent of, but different from, the UV/IR connection in noncommutative field theories [ref] .
UV And IR Effects On Hawking Radiation · UV Cutoff From IR Cutoff · 0.97
Cites it as support 4 papers
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In particular, it is argued [ref] and shown in the light-cone gauge [ref] that the commutative limit ($^2_Θ→^2$) of the noncommutative $=4$ SYM theory is continuous.
A one-loop test for construction of 4D N=4 SYM from 2D SYM via fuzzy sphere geometry · Introduction · 0.97
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Thus it is (expected to be) UV finite, and free of pathological UV/IR mixing [ref] .
Emergent Geometry and Gravity from Matrix Models: an Introduction · Introduction · 1.00
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Particularly well behaved are theories where the gauge fields couple via a star commutator ([ref]) to fermions, as is the case in our model: Cancelations between fermion and boson loops lead to softened UV/IR coupling [ref] .
Photon-neutrino interaction in theta-exact covariant noncommutative field theory · Introduction · 0.98
Cites it as background 22 papers
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For a long time quantum field theories formulated in a Groenewold-Moyal deformed (or $þ$-deformed) space [ref] suffered from new types of divergences arising due to a phenomenon referred to as [ref] .
A New Approach to Non-Commutative U(N) Gauge Fields · Introduction · 0.99
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This phenomenon was first evidenced on the Moyal space in the context of scalar field theories [ref] and shortly extended to noncommutative gauge theories [ref] .
On the UV/IR mixing of Lie algebra-type noncommutatitive $\phi^4$-theories · Introduction · 0.88
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NCFT on noncommutative Moyal spaces received a lot of attention from the end of the 90's, in particular from the viewpoint of perturbative properties and renormalisability [ref] .
Noncommutative gauge theories on $\mathbb{R}^3_\lambda$: Perturbatively finite models · Introduction · 0.98
Discussion
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