REVIEW
Hard Scattering Factorization from Effective Field Theory
High Energy Physics - Phenomenology · Submitted 11 Feb 2002 · 40 references
Pith's verdict: A clean, honest methods paper: the factorization formulae are old, the SCET proof technique for back-to-back jets is the contribution, and the two real gaps are both acknowledged in the text.
T0 · AI review
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Referee report
The paper
The paper claims
Gauge symmetry in an effective theory can carry the proof of hard-scattering factorization, the paper argues, replacing gauge-specific Ward-identity arguments with operator-level decoupling.
The reading
What carries the argument
The machinery is the back-to-back version of soft-collinear effective theory. Collinear quarks and gluons moving in the $n$ direction carry large $n$ labels and small transverse and $n$ components, while fields moving in the $n$ direction carry the opposite large labels; each direction has its own collinear Wilson line, $n$ or $n$, and its own soft Wilson line, $n$ or $n$, with ultrasoft Wilson lines $n$ and $n$ for the lowest-energy gluons. Collinear gauge invariance fixes the placement of $n$ and $n$ in external operators, and the field redefinitions $n$ and $n$ remove ultrasoft gluons from the leading collinear Lagrangian. Integrating out off-shell fluctuations with virtuality of order $n$ induces the soft Wilson lines; the identities $n$ and $n$, plus color identities for octet bilinears, then make the matrix element split into separate collinear matrix elements. That split is the factorization proof.
Extended reading notes
Core claim
The central claim is that the gauge structure of the soft-collinear effective theory, once generalized to back-to-back collinear fields, is enough to establish the factorization formulae for a broad class of hard processes. In each example the hard scattering is matched onto a small set of gauge-invariant operators built from collinear fields and Wilson lines; the soft and ultrasoft Wilson lines either cancel by unitarity or can be moved into one collinear bilinear, so the matrix element factors into a hard coefficient convolved with standard nonperturbative objects. The paper does not present new factorization formulae so much as a new derivation of known ones: the $n$ form factor reduces to a convolution of a hard coefficient with the pion light-cone wavefunction, the meson form factor to two wavefunctions and two hard coefficients, DIS to parton distributions, Drell-Yan to two parton distributions, and DVCS to non-forward parton distributions. The authors emphasize that the argument is gauge independent and valid to all orders in $n$ at leading power.
Load-bearing premise
The load-bearing premise is that Glauber gluons — gluons with momenta of order $(n,n,n)$ exchanged in the $n$-channel between the two collinear directions — can be neglected for all the processes treated here; the paper states this assumption explicitly in Section II.B and cites earlier arguments for Drell-Yan rather than proving it within the effective theory.
Editorial extensions
If this is right
- Factorization proofs for DIS, Drell-Yan, and DVCS can be organized as matching calculations onto a finite set of gauge-invariant SCET operators, with the nonperturbative content isolated in parton distributions or non-forward distributions.
- Exclusive processes such as $n$ and $n$ reduce to convolutions of hard coefficients with light-cone wavefunctions, with the hard coefficients computable by matching.
- The same Wilson-line and field-redefinition steps can be reused across processes, so a proof for one process supplies most of the operator structure for another.
- Because the argument is organized at the operator level, it provides a natural starting point for studying power corrections and for renormalization-group resummation of large logarithms.
- The method covers arbitrary spin and isospin meson form factors at leading power, not just the pion case.
Reading between the lines
- A useful stress test of the framework would be a process where Glauber exchange is kinematically enhanced, such as forward scattering or a region with overlapping jets; if the SCET proof still goes through there, the Glauber assumption would look less like a limitation and more like a theorem.
- The operator-level proof suggests that factorization could be checked mechanically: enumerate the leading-power gauge-invariant operators, apply the Wilson-line identities, and see whether any color-octet bilinear survives between color-singlet states.
- If the back-to-back extension is as general as claimed, it should connect directly to the standard resummation of threshold logarithms in Drell-Yan and DIS, because the same soft Wilson lines control the large logarithms.
- The treatment of DVCS with non-forward distributions hints that the method could be extended to other exclusive processes with unequal incoming and outgoing hadron momenta, provided the same operator basis closes.
Original abstract
In this paper we show how gauge symmetries in an effective theory can be used to simplify proofs of factorization formulae in highly energetic hadronic processes. We use the soft-collinear effective theory, generalized to deal with back-to-back jets of collinear particles. Our proofs do not depend on the choice of a particular gauge, and the formalism is applicable to both exclusive and inclusive factorization. As examples we treat the pi-gamma form factor (gamma gamma* -> pi^0), light meson form factors (gamma* M -> M), as well as deep inelastic scattering (e- p -> e- X), Drell-Yan (p pbar -> X l+ l-), and deeply virtual Compton scattering (gamma* p -> gamma(*) p).
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
In this paper we show how gauge symmetries in an effective theory can be used to simplify proofs of factorization formulae in highly energetic hadronic processes. We use the soft-collinear effective theory, generalized to deal with back-to-back jets of collinear particles. Our proofs do not depend on the choice of a particular gauge, and the formalism is applicable to both exclusive and inclusive factorization. As examples we treat the pi-gamma form factor (gamma gamma* -> pi^0), light meson form factors (gamma* M -> M), as well as deep inelastic scattering (e- p -> e- X), Drell-Yan (p pbar -> X l+ l-), and deeply virtual Compton scattering (gamma* p -> gamma(*) p).
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | In this paper we show how gauge symmetries in an effective theory can be used to simplify proofs of factorization formulae in highly energetic hadronic processes. | contribution 1.00 | 0.94 | 0.81 | asserted 1.00 |
| s1 | We use the soft-collinear effective theory, generalized to deal with back-to-back jets of collinear particles. | method 0.96 | 0.84 | 0.05 | asserted 0.99 |
| s2 | Our proofs do not depend on the choice of a particular gauge, and the formalism is applicable to both exclusive and inclusive factorization. | result 0.42 | 0.91 | 0.22 | asserted 1.00 |
| s3 | As examples we treat the pi-gamma form factor (gamma gamma* -> pi^0), light meson form factors (gamma* M -> M), as well as deep inelastic scattering (e- p -> e- X), Drell-Yan (p pbar -> X l+ l-), and deeply virtual Compton scattering (gamma* p -> gamma(*) p). | contribution 0.93 | 0.83 | 0.05 | asserted 0.98 |
What was examined, and what was not
- arXiv listing abstract v2
- full text
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- references and citing sentences
- relations to other papers
- P abstract
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Figures
Figures reproduced from arXiv:hep-ph/0202088 by the authors.
References
How later papers used it
366 later papers cite it
1 later paper by other authors is listed below: 1 used its method or tool. 2 more papers by the same authors are listed: 2 used its method or tool.
Uses its method or tool 3 of 59 papers with this label · 2 by the same authors
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Followed this paper in starting with the unpolarized Drell-Yan cross section.
Effective field theories for quantum chromo- and electrodynamics (2016) · 0.98 · paraphrased: the licence does not allow quoting
By the same authors
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Constructed its basis post BPS field redefinition, which is this paper's field redefinition performed in each collinear sector.
A Subleading Power Operator Basis for the Scalar Quark Current (2017) (same authors) · 0.94 · paraphrased: the licence does not allow quoting
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Constructed its basis post BPS field redefinition, which is defined by this paper and performed in each collinear sector.
A Subleading Operator Basis and Matching for $gg \to H$ (2017) (same authors) · 0.87 · paraphrased: the licence does not allow quoting
How the literature uses it
359 arXiv papers cite this in 483 sentences
Papers citing it · 281 sentences without a confident label
Builds on it 4 papers
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Here we extend the work of Ref. [ref] by setting up a factorization framework within Soft Collinear Effective Theory (SCET) [ref] , which allows for the systematic extension beyond LL.
The soft drop momentum sharing fraction $z_g$ beyond leading-logarithmic accuracy · Introduction · 0.91
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In this paper we develop such a factorization and resummation framework for generic jet hierarchies in hard-scattering processes with large momentum transfer by considering an extension of Soft-Collinear Effective Theory (SCET) [ref] referred to as .
Factorization and Resummation for Generic Hierarchies between Jets · Introduction · 0.81
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By extension from SCET [ref] , two collinear sectors in $$, $n_1$ and $n_2$, are distinct if
Systematic Improvement of Parton Showers with Effective Theory · Finite RPI · 0.89
Uses its method or tool 56 papers
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It requires the combination of numerically robust NNLO Drell-Yan-plus-jet production evaluated at low transverse momentum cut-off [ref] with unresolved N$^3$LO contributions including logarithmic divergent terms [ref] predicted via Soft-Collinear Effective Theory (SCET) [ref] .
Differential N$^3$LO QCD corrections to charged current production at the LHC · Implementation · 0.81
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[ref] using soft-collinear effective theory (SCET) [ref] .
Impact of Jet Veto Resummation on Slepton Searches · Jet veto resummation · 0.99
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We apply the TMD factorization formula [ref] derived in soft-collinear effective theory (SCET) [ref] to obtain the N$^3$LL resummation formula, and the $𝒪(α_s^2)$ fixed-order matching distribution is obtained using the NLOJET++ event generator [ref] .
N$^{\mathbf{3}}$LL + $\mathcal{O}(\alpha_s^2)$ predictions of lepton-jet azimuthal angular distribution in deep-inelastic scattering · Introduction · 0.99
Compares with it 3 papers
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This differs conceptually from the standard SCET construction [ref] , in which the scaling of all momentum components follows from the on-shell condition and the associated power counting.
Color Coherence and the Soft Structure of QCD Jets in Vacuum and the QGP · Separation of vacuum and medium time scales · 0.86
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The beam function definitions in B_def can be compared with those of the standard quark, antiquark, and gluon PDFs in SCET [ref] ,
Factorization at the LHC: From PDFs to Initial State Jets · The Beam Function · 0.99
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Because of time-ordered product contributions from diagrams with onshell propagators in the EFT these matching calculations are more non-trivial than the SCET matching done to yield Wilson lines in Refs. [ref] .
An Effective Field Theory for Forward Scattering and Factorization Violation · Guide for the Reader · 0.85
Cites it as background 126 papers
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For this purpose, soft-collinear effective theory (SCET) [ref] has been developed and widely used until now.
Dijet invariant mass distribution near threshold · Introduction · 0.81
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Another option is to use the $N$-jettiness variable [ref] , first introduced in the context of Soft Collinear Effective Theory (SCET) [ref] , to distinguish processes with a different number of jets.
Beam functions for $N$-jettiness at N$^3$LO in perturbative QCD · Introduction · 0.92
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For a detailed discussion of the effective Lagrangian of SCET-1, including the leading power corrections, we refer the reader to the founding papers [ref] (see [ref] for a review).
The Simplest B Decay, Precisely · Matching to Soft-Collinear Effective Theory · 0.93
Discussion
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