arxiv: 2510.05420 · v2 · submitted 2025-10-06 · ✦ hep-ph

Dissociative associated J/psi and dimuon production in Ap ultraperipheral collisions via double parton scattering

Bruna O. Stahlh\"ofer , Edgar Huayra , Emmanuel G. de Oliveira This is my paper

Pith reviewed 2026-05-18 08:42 UTC · model grok-4.3

classification ✦ hep-ph

keywords ultraperipheral collisionsdouble parton scatteringJ/psi productiondimuon productiondissociative productioneffective cross sectionpocket formulaLHC predictions

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The pith

A pocket formula describes dissociative J/ψ and dimuon production via double parton scattering in ultraperipheral nucleus-proton collisions.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper establishes that dissociative associated production of a J/ψ meson and dimuon in nucleus-proton ultraperipheral collisions occurs through double parton scattering with a rapidity gap. This channel is sensitive to the photon and gluon distributions of the proton. A DPS pocket formula is derived together with an expression for the effective cross section. The kinematic dependence of that effective cross section is shown, and differential cross section predictions are presented for LHC and FCC energies.

Core claim

In nucleus-proton ultraperipheral collisions the dissociative associated production of J/ψ and dimuon proceeds via double parton scattering, for which a pocket formula is derived together with the corresponding effective cross section, enabling demonstration of its kinematic dependence and predictions of differential DPS cross sections at LHC and FCC energies.

What carries the argument

The DPS pocket formula for this associated J/ψ and dimuon production, which supplies a simplified expression for the cross section by combining the nuclear photon flux with the proton gluon distributions under double parton scattering.

If this is right

The effective cross section depends on the kinematics of the produced particles in a calculable way.
Differential cross sections can be predicted for the energies reached at the LHC and the Future Circular Collider.
The channel gives direct access to the gluon distributions inside the proton.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

Pocket formulas of the same form could be written for other dissociative vector-meson plus lepton-pair final states to probe additional parton distributions.
Higher-energy runs might expose how nuclear modifications alter the size of the effective cross section in ultraperipheral collisions.
The rapidity-gap tag could be used to isolate double parton scattering contributions in other heavy-ion or proton-nucleus systems.

Load-bearing premise

Dissociative associated J/ψ and dimuon production proceeds dominantly via double parton scattering with a clear rapidity gap that permits clean factorization between the nuclear photon flux and the proton's gluon distributions.

What would settle it

LHC data that either lack the predicted rapidity gap in the J/ψ and dimuon events or show an effective cross section whose kinematic dependence deviates from the derived expression would indicate that double parton scattering is not the dominant mechanism.

Figures

Figures reproduced from arXiv: 2510.05420 by Bruna O. Stahlh\"ofer, Edgar Huayra, Emmanuel G. de Oliveira.

**Figure 2.** Figure 2: FIG. 2: Photon distributions of the proton on the impact-parameter [PITH_FULL_IMAGE:figures/full_fig_p006_2.png] view at source ↗

**Figure 3.** Figure 3: FIG. 3: Differential cross section for dimuon ( [PITH_FULL_IMAGE:figures/full_fig_p007_3.png] view at source ↗

**Figure 4.** Figure 4: FIG. 4: Dissociative and inelastic [PITH_FULL_IMAGE:figures/full_fig_p009_4.png] view at source ↗

**Figure 5.** Figure 5: FIG. 5: SPS dissociative [PITH_FULL_IMAGE:figures/full_fig_p010_5.png] view at source ↗

**Figure 6.** Figure 6: FIG. 6: DPS effective cross section in [PITH_FULL_IMAGE:figures/full_fig_p012_6.png] view at source ↗

**Figure 7.** Figure 7: FIG. 7: DPS cross section for [PITH_FULL_IMAGE:figures/full_fig_p013_7.png] view at source ↗

**Figure 8.** Figure 8: FIG. 8: Comparison of DPS ( [PITH_FULL_IMAGE:figures/full_fig_p014_8.png] view at source ↗

**Figure 9.** Figure 9: FIG. 9: DPS cross section for double [PITH_FULL_IMAGE:figures/full_fig_p017_9.png] view at source ↗

read the original abstract

We study the dissociative associated production of a $J/\psi$ meson and a dimuon via double parton scattering (DPS) in nucleus--proton ultraperipheral collisions. This new channel, characterized by a rapidity gap, is sensitive to the photon and gluon distributions of the proton. We derive a DPS pocket formula for this process, together with a corresponding expression for the effective cross section. Furthermore, we demonstrate the kinematic dependence of the effective cross section and present predictions for the differential DPS cross section at LHC and FCC energies.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

The paper carves out a new DPS channel for dissociative J/ψ + dimuon in Ap UPCs and supplies a pocket formula plus effective cross section, but the derivation leans on untested dominance and factorization assumptions.

read the letter

The main thing here is that the authors flag a fresh final state—dissociative associated J/ψ plus dimuon—in nucleus-proton ultraperipheral collisions and treat it as double parton scattering. They write down a pocket formula, give an expression for the effective cross section, map its kinematic dependence, and show some cross-section predictions at LHC and FCC energies. That combination of the nuclear photon flux with the proton’s gluon distributions through DPS is the concrete step they take beyond earlier work on separate DPS or UPC processes. The rapidity-gap characterization is a reasonable way to frame the observable, and the kinematic plots give experimenters something to look at when planning measurements. The extension itself is straightforward and internally consistent on its own terms. The softer spot is the lack of explicit checks on the central assumptions. The pocket formula and effective cross section rest on DPS being dominant and on clean factorization once the gap is present, yet the text does not appear to include quantitative bounds on single-parton-scattering contributions, photon-exchange interference, or nuclear-breakup effects that could fill the gap or spoil the separation. Without those estimates or a comparison to data, it is difficult to judge how directly the quoted effective cross section applies in the kinematics they consider. The predictions therefore stay somewhat preliminary. This is niche work aimed at people already doing DPS phenomenology or UPC calculations in heavy-ion physics. A reader who knows the existing effective-cross-section literature will see the value in the new channel and the kinematic study, but it will not reorganize the broader field. It deserves a serious referee because the channel is new and the calculations are laid out clearly enough that a review can test the assumptions and ask for the missing bounds. I would send it to review rather than desk-reject it.

Referee Report

1 major / 1 minor

Summary. The manuscript studies dissociative associated production of a J/ψ meson and a dimuon via double parton scattering (DPS) in nucleus-proton ultraperipheral collisions. It derives a DPS pocket formula together with an expression for the effective cross section, demonstrates the kinematic dependence of the effective cross section, and presents predictions for differential DPS cross sections at LHC and FCC energies.

Significance. If the central assumptions hold, the work introduces a new channel in ultraperipheral collisions characterized by a rapidity gap and sensitive to both photon and gluon distributions. The derivation of a pocket formula and the corresponding effective-cross-section expression, together with explicit predictions at collider energies, would provide a compact framework for testing DPS phenomenology in a relatively clean environment.

major comments (1)

[Abstract and DPS pocket formula derivation section] The derivation of the pocket formula (abstract and the section presenting the DPS formula) assumes that dissociative associated production proceeds dominantly via DPS with a clear rapidity gap and clean factorization between the nuclear photon flux and proton gluon distributions. No explicit estimate, suppression factor, or upper bound is given for single-parton-scattering (SPS) contributions, photon-exchange interference, or nuclear-breakup effects that could fill the gap or invalidate the factorization. This assumption is load-bearing for the applicability of both the pocket formula and the quoted effective cross section.

minor comments (1)

[Abstract] The abstract states that the effective cross section's kinematic dependence is demonstrated, but does not indicate whether this dependence is parameter-free or derived from first principles; a short clarifying phrase would help readers.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for the careful reading of our manuscript and for the constructive major comment. We address the point raised below and indicate the changes we will make in the revised version.

read point-by-point responses

Referee: [Abstract and DPS pocket formula derivation section] The derivation of the pocket formula (abstract and the section presenting the DPS formula) assumes that dissociative associated production proceeds dominantly via DPS with a clear rapidity gap and clean factorization between the nuclear photon flux and proton gluon distributions. No explicit estimate, suppression factor, or upper bound is given for single-parton-scattering (SPS) contributions, photon-exchange interference, or nuclear-breakup effects that could fill the gap or invalidate the factorization. This assumption is load-bearing for the applicability of both the pocket formula and the quoted effective cross section.

Authors: We agree that the derivation of the pocket formula and the effective cross section rests on the assumption of DPS dominance with a clear rapidity gap and factorization between the nuclear photon flux and proton parton distributions. The current manuscript does not provide explicit numerical estimates, suppression factors, or upper bounds for SPS contributions, photon-exchange interference, or nuclear-breakup effects. In the revised version we will add a dedicated paragraph after the derivation of the pocket formula that discusses the expected suppression of SPS in this channel (arising from the requirement of a large rapidity gap and the color-singlet nature of the J/ψ), together with order-of-magnitude estimates drawn from analogous DPS/SPS comparisons in the literature. We will also include a short discussion of why photon-exchange interference and nuclear-breakup contributions are expected to remain small for the selected kinematics and impact-parameter range typical of ultraperipheral collisions, with references to existing studies of gap survival in UPCs. These additions will clarify the domain of applicability without changing the central DPS results. revision: yes

Circularity Check

0 steps flagged

No significant circularity; derivation presented as independent

full rationale

The paper states it derives a DPS pocket formula and effective cross-section expression for the new dissociative associated production channel in Ap UPCs. The abstract and summary describe this as a direct derivation sensitive to photon and gluon distributions, with predictions for differential cross sections at LHC/FCC energies. No self-citations are invoked as load-bearing for the central premise, no fitted parameters are relabeled as predictions, and no ansatz or uniqueness theorem is smuggled in. The derivation chain appears self-contained against external benchmarks, with the effective cross section's kinematic dependence presented as a new result rather than a tautology or renormalization to prior data. This is the expected honest non-finding for a phenomenology paper introducing a new channel.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The central claim rests on standard high-energy QCD assumptions for ultraperipheral collisions and double parton scattering; no new free parameters or invented entities are introduced in the abstract.

axioms (2)

domain assumption Double parton scattering can be treated with a pocket formula that factorizes nuclear photon flux from proton gluon distributions
Invoked when the authors state they derive the DPS pocket formula for the process.
domain assumption A rapidity gap cleanly isolates the dissociative associated production channel
Stated as characterizing the new channel in the abstract.

pith-pipeline@v0.9.0 · 5628 in / 1257 out tokens · 46454 ms · 2026-05-18T08:42:23.102227+00:00 · methodology

discussion (0)

Reference graph

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