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Evading Sudakov Dilution in Gluon Tomography

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ReviewThe objections and verdict, as JSON Paper breakdownThe authors' claims, conditions and measurements, as JSON Signed receiptProof this review has not been altered
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Shuo Lin, Jian Zhou

High Energy Physics - Phenomenology · Submitted 2 Sep 2026 · 66 references

Pith's verdict: Clever observable for gluon TMDs, but the central claim about inside-interval emissions cancelling in the azimuthal harmonic is unproven when jet axis deflection is considered.

T0 · AI review

How this review was made: An AI referee (deepseek/deepseek-v4-flash) read the paper on September 8, 2026 and answered a fixed list of questions about it. T0 is the starting level every paper gets. The levels describe how deeply Pith has checked the paper, never the authors.

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  2. T1 Audit Automatic checks that the references and files the paper relies on exist and match.
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  4. T3 Formal statement The claims written out in a formal math language a computer can read.
  5. T4 Proof Those claims proved, and the proof checked by computer.

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arXiv ID2609.02280 (version 1)
Pith IDTKJHIPXP, Pith's permanent record of this paper and its review
CitationJian Zhou, Shuo Lin. "Evading Sudakov Dilution in Gluon Tomography." arXiv:2609.02280 (2026). https://pith.science/paper/TKJHIPXP
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The paper

The paper claims

Fiducial hadronic recoil suppresses Sudakov dilution and boosts gluon TMD signal 4.6 times.

The reading

Since gluon transverse-momentum-dependent distributions like the linearly polarized $h_1^{{⊥g}}$ are diluted by Sudakov broadening and competing azimuthal harmonics from final-state soft radiation, existing methods cannot cleanly access $h_1^{{⊥g}}$. This paper shows that using the vector sum of all hadronic transverse momenta within a limited rapidity interval (fiducial hadronic recoil) as the measured observable, with a single tagged jet setting the azimuthal reference, eliminates the broadening and harmonics from radiation inside the interval. Momentum conservation ensures that only radiation outside the interval contributes. For a rapidity interval of width Δη=3, the signal is enhanced 4.6-fold and the contaminating term suppressed 4.0-fold compared to the conventional dijet imbalance. This provides a new experimental strategy for precision gluon tomography at the Electron-Ion Collider.

What carries the argument

The key object is the fiducial hadronic recoil vector l = Σ_{|η_h|≤Δη/2} p_h. Its definition relies on momentum conservation: the incoming gluon transverse momentum κ and the sum of out-of-interval radiation determine l, while inside-interval emissions cancel in the sum. The second key element is the angular antenna A_2(η)=$e^{{-2|η|}}$ A_0(η) for the cos2φ projection, which shows that the harmonic weight of a soft emission decays exponentially with rapidity separation from the outgoing partons.

Extended reading notes

Core claim

The central claim is that fiducial hadronic recoil—the transverse-momentum vector sum of all hadrons in a chosen rapidity interval—simultaneously suppresses both Sudakov broadening and the final-state soft-gluon cos 2φ harmonic that contaminate gluon-TMD observables such as $h_1^{{⊥g}}$ in DIS. The mechanism is momentum conservation: emissions inside the interval are included in the sum and therefore cause no recoil broadening or azimuthal harmonic. Widening the interval reduces the phase space for out-of-interval radiation exponentially. For Δη=3 and l_T=2 GeV, the $h_1^{{⊥g}}$ contribution to the cos2φ moment is enhanced by a factor 4.6 and the final-state soft-gluon term reduced by a factor 4.0 relative to using the R=0.4 dijet imbalance.

Load-bearing premise

The calculation assumes that soft radiation inside the fiducial interval does not deflect the reconstructed axis of the tagged jet, so the azimuthal angle of the recoil relative to the jet axis remains unaltered by inside-interval emissions.

Editorial extensions

If this is right

  • At an EIC with typical kinematics (Q=10 GeV, P_T=15 GeV), the fiducial recoil with Δη=3 gives a 4.6× larger h_1^{⊥g} signal in the cos2φ moment than the standard dijet imbalance, and reduces the soft-gluon background by a factor 4.0, making h_1^{⊥g} accessible without vetoing soft radiation.
  • Because the cancellation is spin-independent, the same strategy applies to other leading-twist gluon TMDs in processes with different beam and target polarizations and azimuthal projections.
  • Experimentally, only one tagged jet is needed; the second hard parton needs only to be verified to fall inside the interval, not to be reconstructed with high precision.
  • The azimuthally averaged recoil spectrum also shows enhanced low-l_T yield, improving statistics for unpolarized TMD extraction.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • The approach could be extended to pp collisions by defining a similar fiducial rapidity interval for the hadronic recoil, though the presence of multiple color-connected hard legs may complicate the cancellation for inside-interval radiation.
  • A similar strategy might improve measurements of other TMDs, such as the Sivers or Boer-Mulders functions, by suppressing final-state soft-gluon harmonics in processes where they contribute.
  • The method relies on the assumption that soft radiation inside the interval does not significantly alter the reconstructed jet axis; a full simulation with parton showers could test the validity at finite jet radius.
Original abstract

Sudakov broadening and competing azimuthal harmonics from final-state soft radiation limit the precision of gluon tomography. We suppress both effects using fiducial hadronic recoil---the vector sum of all hadronic transverse momenta within a rapidity interval---while a tagged jet fixes the azimuthal axis. Momentum conservation ensures that emissions inside the interval contribute neither to recoil broadening nor to these harmonics, so widening the interval reduces their impact without a soft-radiation veto. As a benchmark, we study the $\cos 2\phi$ modulation probing $h_1^{\perp g}$ in DIS. For rapidity interval $\Delta\eta=3$, fiducial recoil enhances the $h_1^{\perp g}$ contribution by a factor of $4.6$ and suppresses the final-state soft gluon term by a factor of $4.0$ relative to the conventional dijet imbalance. Fiducial recoil thereby enables precision gluon-TMD tomography.

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.

Compiled by classifier-1.13.0 via TypeSafe API, question bank abstract-p1-20260923, 2026-09-23: 1 request, 5,041 input tokens.

What the abstract itself states, as probabilities: claims first 0.04 · states limitation 0.17 · human participants 0.02 · controlled comparison 0.87 · randomized assignment 0.01 · states quantitative result 0.98 · compares with prior results 0.95 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v1. Results and the main claim are underlined; .

Sudakov broadening and competing azimuthal harmonics from final-state soft radiation limit the precision of gluon tomography. We suppress both effects using fiducial hadronic recoil---the vector sum of all hadronic transverse momenta within a rapidity interval---while a tagged jet fixes the azimuthal axis. Momentum conservation ensures that emissions inside the interval contribute neither to recoil broadening nor to these harmonics, so widening the interval reduces their impact without a soft-radiation veto. As a benchmark, we study the $\cos 2\phi$ modulation probing $h_1^{\perp g}$ in DIS. For rapidity interval $\Delta\eta=3$, fiducial recoil enhances the $h_1^{\perp g}$ contribution by a factor of $4.6$ and suppresses the final-state soft gluon term by a factor of $4.0$ relative to the conventional dijet imbalance. Fiducial recoil thereby enables precision gluon-TMD tomography.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#sentencerolethe authors' own workstates the main conclusionstrength
s0 Sudakov broadening and competing azimuthal harmonics from final-state soft radiation limit the precision of gluon tomography. background 1.00 0.06 0.03 asserted 1.00
s1 We suppress both effects using fiducial hadronic recoil---the vector sum of all hadronic transverse momenta within a rapidity interval---while a tagged jet fixes the azimuthal axis. method 0.95 0.87 0.14 asserted 1.00
s2 Momentum conservation ensures that emissions inside the interval contribute neither to recoil broadening nor to these harmonics, so widening the interval reduces their impact without a soft-radiation veto. method 0.83 0.43 0.14 asserted 1.00
s3 As a benchmark, we study the $\cos 2\phi$ modulation probing $h_1^{\perp g}$ in DIS. contribution 0.67 0.76 0.02 asserted 0.93
s4 For rapidity interval $\Delta\eta=3$, fiducial recoil enhances the $h_1^{\perp g}$ contribution by a factor of $4.6$ and suppresses the final-state soft gluon term by a factor of $4.0$ relative to the conventional dijet imbalance. result 1.00 0.92 0.16 asserted 1.00
s5 Fiducial recoil thereby enables precision gluon-TMD tomography. interpretation 0.99 0.48 0.92 asserted 1.00

What kind of paper the classifier reports this is: method or tool 0.98 · evidence from argument 0.45.

What was examined, and what was not

sources read
  • arXiv listing abstract v1
not examined
  • full text
  • figures and tables
  • references and citing sentences
  • relations to other papers
levels run
  • P abstract
not run
  • S sections
  • T body sentences
  • C citations
  • R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

Figures
Figure 1. FIG. 1. Schematic of the hadronic-recoil measurement in
Figure 2. FIG. 2. Azimuthally averaged hadronic-recoil spectra for
Figure 4. FIG. 4. Hadronic-recoil

Showing 3 of the paper's 4 figures. See all figures in the PDF ↗ Figures reproduced from arXiv:2609.02280 by the authors.

References

Discussion

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