REVIEW
Renormalons
High Energy Physics - Phenomenology · Submitted 21 Jul 1998 · 164 references
Pith's verdict: The standard reference on renormalons, and it earns that status: the scaling-not-normalization thesis is right, and the paper is unusually honest about where the arguments stop being proofs.
T0 · AI review
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Referee report
The paper
The paper claims
The factorial divergence of perturbative QCD series is not noise: it encodes where non-perturbative power corrections must appear, and at what power of the hard scale.
The reading
What carries the argument
The Borel transform $B[R](t) = sum_n r_n t^n / n!$ turns factorial growth into singularities, and the variable $u = -beta_0 t$ places infrared renormalons at positive integer or half-integer $u$ and ultraviolet ones at negative $u$. The calculational engine is the flavour ($1/N_f$) expansion, in which a chain of fermion bubbles becomes an analytically regularized gluon propagator of power $1+u$; the singularity structure of multi-chain diagrams then follows from a forest formula identical in shape to the standard ultraviolet renormalization recursion, with dimension-6 operators playing the role of counterterms. Renormalization-group analysis upgrades this to a statement valid beyond the flavour expansion: the coefficient functions of the compensating operators solve a linear equation whose kernel is the $\beta$ function and the anomalous-dimension matrix of dimension-6 operators, so everything except the integration constants is determined. For phenomenology the review prefers the dispersive or 'massive gluon' representation, in which the whole bubble chain is resummed into an effective coupling $Phi(xi)$ integrated against a characteristic function $T(xi)$; non-analytic terms in the small-$xi$ expansion of $T$ map one-to-one onto power corrections, so the correspondence can be read off without evaluating the Borel integral.
Extended reading notes
Core claim
The review's organizing thesis is that infrared renormalons in perturbative coefficient functions are the perturbative shadow of non-perturbative power corrections. Concretely: if a skeleton diagram behaves as $F(k^2) + O(k^a)$ at small loop momentum, then dressing it with fermion bubbles produces a Borel singularity at $u = a/2$ (with $u = -beta_0 t$) and a corresponding Borel-integral ambiguity scaling as $(Lambda/Q)^a$. The position of the singularity, and hence the power of the correction, is calculable; the residue is not, because it receives unsuppressed contributions from diagrams with arbitrarily many chains. The review supports this with a solvable case, the $O(N)$ non-linear $\sigma$ model in the $1/N$ expansion, where the cancellation between the renormalon ambiguity of the coefficient function and the power-divergent part of the operator matrix element can be followed exactly, and with a one-loop QCD check in which the quadratic divergence of twist-4 three-particle operators reproduces the leading infrared renormalon of the longitudinal deep-inelastic structure function. A parallel argument covers ultraviolet renormalons: they can be compensated by higher-dimension operator insertions, in direct analogy with Symanzik improvement of lattice actions, and in QCD they are sign-alternating and harmless.
Load-bearing premise
The quantitative reading of the Borel plane assumes that the subtraction scheme used to define the coupling is 'regular', meaning its subtraction constants do not themselves diverge factorially; the review states that this is reasonable and true to leading order in the flavour expansion, but that there is no proof for the minimal-subtraction scheme, since that scheme is defined only order by order.
Editorial extensions
If this is right
- The leading power correction to a class of observables is fixed in its $Q$-dependence by the position of the nearest infrared renormalon, giving $1/Q$ corrections to event-shape variables, $1/m$ to the heavy-quark pole mass, and $1/Q^2$ to twist-4 structure functions without non-perturbative input.
- For observables that share the same operator, the ratio of power corrections is computable in perturbation theory from the lowest-order coefficient functions, so only one overall number per operator has to be taken from data.
- Ultraviolet renormalons can be absorbed into higher-dimension operators with calculable anomalous dimensions, so their factorial growth does not require new non-perturbative parameters, only a choice of renormalization scale.
- The scheme dependence of the uncalculable normalization is one-loop and known explicitly, so a normalization fixed in one scheme can be transported to another once the relation between couplings is specified.
- Where a hard process admits an operator product expansion, renormalons add nothing beyond what the condensate expansion already says; their value lies in processes such as fragmentation and event shapes that have no operator interpretation.
Reading between the lines
- If the normalization is genuinely non-computable in QCD, the natural place to obtain it is the lattice: a numerical determination of the gluon condensate or of the relevant non-local soft matrix element would convert renormalon-inspired models from one-parameter fits into parameter-free predictions, and would test the whole chain rather than just its scaling.
- The position prediction needs only the first beta-function coefficient, so the same bookkeeping should transfer to any asymptotically free theory with a known one-loop beta function, including lower-dimensional or condensed-matter critical systems; the cheap part of the prediction travels, the hard part (the residue) does not.
- The pattern of successes and failures catalogued for event shapes suggests the modelling is most trustworthy when the leading infrared region is a single soft gluon coupling to eikonal lines, and least trustworthy when several partons go soft at once; that is a testable regularity, since one can sort observables by the number of lines in their soft subgraph and check whether the model's accuracy d
- Because the review ties the infrared renormalon to the ultraviolet power divergence of the corresponding operator, a lattice calculation that subtracts power divergences non-perturbatively and one that does not should disagree by exactly the renormalon ambiguity; that disagreement is a measurable quantity rather than a bookkeeping artefact.
Original abstract
A certain pattern of divergence of perturbative expansions in quantum field theories, related to their small and large momentum behaviour, is known as renormalons. We review formal and phenomenological aspects of renormalon divergence. We first summarize what is known about ultraviolet and infrared renormalons from an analysis of Feynman diagrams. Because infrared renormalons probe large distances, they are closely connected with non-perturbative power corrections in asymptotically free theories such as QCD. We discuss this aspect of the renormalon phenomenon in various contexts, and in particular the successes and failures of renormalon-inspired models of power corrections to hard processes in QCD.
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 certain pattern of divergence of perturbative expansions in quantum field theories, related to their small and large momentum behaviour, is known as renormalons. We review formal and phenomenological aspects of renormalon divergence. We first summarize what is known about ultraviolet and infrared renormalons from an analysis of Feynman diagrams. Because infrared renormalons probe large distances, they are closely connected with non-perturbative power corrections in asymptotically free theories such as QCD. We discuss this aspect of the renormalon phenomenon in various contexts, and in particular the successes and failures of renormalon-inspired models of power corrections to hard processes in QCD.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | A certain pattern of divergence of perturbative expansions in quantum field theories, related to their small and large momentum behaviour, is known as renormalons. | background 1.00 | 0.04 | 0.05 | asserted 1.00 |
| s1 | We review formal and phenomenological aspects of renormalon divergence. | contribution 0.98 | 0.64 | 0.05 | asserted 0.51 |
| s2 | We first summarize what is known about ultraviolet and infrared renormalons from an analysis of Feynman diagrams. | method 0.46 | 0.17 | 0.04 | asserted 0.93 |
| s3 | Because infrared renormalons probe large distances, they are closely connected with non-perturbative power corrections in asymptotically free theories such as QCD. | background 0.90 | 0.07 | 0.11 | asserted 1.00 |
| s4 | We discuss this aspect of the renormalon phenomenon in various contexts, and in particular the successes and failures of renormalon-inspired models of power corrections to hard processes in QCD. | contribution 0.97 | 0.54 | 0.14 | asserted 0.52 |
What was examined, and what was not
- arXiv listing abstract v2
- 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-ph/9807443 by the authors.
References
How later papers used it
219 later papers cite it
1 later paper by other authors is listed below: 1 used its method or tool.
Uses its method or tool 1 of 8 papers with this label
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Estimated the large order behavior using the Naive non-abelianization, with delta_n approximately zero for n at least 4, to estimate d_n to all orders from the fermion bubble graphs.
The QCD Adler function and the muon $g-2$ anomaly from renormalons (2021) · 0.96 · paraphrased: the licence does not allow quoting
How the literature uses it
210 arXiv papers cite this in 414 sentences
Papers citing it · 243 sentences without a confident label
Contests it 3 papers
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This is the first point where our construction is in sharp disagreement with the widely accepted perspective [ref] which asserts that the leading non-BPS semi-classic configuration in the $SU(N)$ theory must have an action $2S_I$
TQFT at work for IR-renormalons, resurgence and Lefschetz decomposition · Introduction · contest 0.79
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(The heavy quark whose mass is considered here is decoupled.) The constants that appear in ([ref]) are given by [ref] $b=-β_1/(2β_0^2)$ and [equation] Note that we have corrected some misprints in the expression for $b$ and $s_2$ given in [ref] (eqs.
On the ultimate uncertainty of the top quark pole mass · Summary of formulae · contest 0.86
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[ref] , where the scalar correlation function has been calculated in the large-$N_f$ approximation [ref] , or relatedly the large-$β_0$ approximation [ref] (for a review see [ref] ), to all orders in the strong coupling.[For historical reasons, we shall speak about the “large-$β_0$” approximation, although in the notation employed in this work, the leading coefficient of the $β$-function is termed $β_1$.] However, as will be discussed in more detail below, the large-$β_0$ approximation does not provide a satisfactory representation of the scalar correlator in full QCD.
Scalar correlator, Higgs decay into quarks, and scheme variations of the QCD coupling · Introduction · contest 0.75
Builds on it 1 paper
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[ref] , but closely follows the material already presented there and in part in the review [ref] .
Higher-order behaviour of two-point current correlators · General renormalon-pole structure · 0.90
Uses its method or tool 8 papers
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We estimate the large order behavior in Eq. [ref] using the “Naive non-abelianization”, namely the $δ_n∼0$ for $n≥4$, such that we are able to estimate $d_n$ to all orders from the fermion bubble graphs [ref] .
The QCD Adler function and the muon $g-2$ anomaly from renormalons · Introduction · 0.96
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Using standard RG arguments (see e.g. [ref] ), and evaluating the non-perturbative correction at $μ=Q$, we find
Renormalons in integrable field theories · Large order behavior from renormalons · 0.81
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Indeed, in such cases the appearance of linear power corrections can be investigated by computing $𝒪(α_s)$ corrections to the process (and observable) under consideration that originate from virtual exchanges and real emissions of massive gluons, in the limit of a small gluon mass $λ$, see Ref. [ref] .[Since by assumption the underlying process does not contain gluons, this does not lead to any issue with gauge invariance.] The presence of terms that are linear in $λ$ implies that a particular observable receives leading power corrections that are of the type $𝒪(Λ_QCD/Q)$, while their absence can be interpreted as an indication that non-perturbative corrections are further suppressed.
On linear power corrections in certain collider observables · Introduction · 0.84
Uses its data or values 2 papers
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The Adler function is known up to $n=3$ [ref] or up to $𝒪(α_s^4)$, from which the coefficients $d_n$ and $δ_n$ can be taken from Ref. [ref] .
The QCD Adler function and the muon $g-2$ anomaly from renormalons · Introduction · 0.83
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where $ν=2β_1/β_0^2$, and the following large-$β_0$ result is used [ref] : C_0=3/4C_F e^10/3 .
Flavor dependence of normalization constant for an infrared renormalon · Introduction · 0.99
Compares with it 6 papers
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This result is identical to the leading renormalon in the pole mass (see for instance Refs. [ref] ).
A discussion on leading renormalon in the pole mass · Leading renormalon from recurrence relation · 0.83
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The recent estimate of the ambiguity in Ref. [ref] following the prescription of [ref] is about $60%$ smaller and coincides with the size of the minimal correction term $Δ(n_min)$ and also the scale variation at $(α_s^min)$ for $R=163$ GeV.
On the Light Massive Flavor Dependence of the Top Quark Mass · Pole Mass Ambiguity · 0.95
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The coefficients $g_ℓ$ agree with the coefficients $s_ℓ$ given in Refs. [ref] .
The MSR Mass and the ${\cal O}(\Lambda_{\rm QCD})$ Renormalon Sum Rule · QCD beta-Function and Coefficients · 0.94
Cites it as support 2 papers
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This procedure is scheme-independent and leads to results free from divergent renormalon terms [ref] .
Elimination of QCD Renormalization Scale and Scheme Ambiguities · Introduction · 0.97
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The divergent pattern can be inferred alternatively from particular classes of Feynman diagrams, which indicate a factorial growth of the expansion coefficients in both QED [ref] , [ref] and QCD [ref] , [ref] , [ref] .
Conformal mappings in perturbative QCD · Introduction · 0.96
Cites it as background 105 papers
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These singularities are the renormalons of perturbation theory [ref] .
Renormalons in integrated spectral function moments and $\alpha_s$ extractions · Introduction · 0.99
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[ref] , based on renormalon calculus [ref] .
A note on renormalon models for the determination of alpha_s(M_tau) · Introduction · 0.86
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Analytical models based on renormalons [ref] have in the past been met with great success in the description of LEP and HERA event-shape variables [ref] , but have not really been utilised outside that context.
Hadronisation corrections for jets in the k_t algorithm · Introduction · 0.97
Discussion
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