{"id":"f2eba79d-ba75-4b20-a0c3-6d8cd89167cf","arxiv_id":"2510.10318","paper_version":2,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":5.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":5,"one_line_summary":"NLO corrections suppress exclusive γγ→J/ψ+γ production in pp UPCs by ~20-36%, still yielding ~1000 observable signal events at the HL-LHC.","lead":"This paper calculates next-to-leading-order QCD corrections to exclusive J/psi-plus-photon production in photon-photon collisions at the LHC, using NRQCD with an impact-parameter-dependent photon flux. It predicts the process remains observable at the HL-LHC, but only the proton-proton case is actually presented despite an abstract promising heavier-ion systems.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"NLO real-gluon emission phase space is undefined; exclusive cross sections not reproducible.","rationale":"The reader's verdict correctly identifies the unaddressed real-gluon emission as the central weakness. I agree: the NLO numbers in Table 1 are the paper's main result, and every phenomenological statement (event yields, suppression pattern) depends on them. Without a defined IR-cancellation prescription, the cross-section definition is ambiguous, which is a correctness risk, not a stylistic overclaim. The second major issue—the disconnect between the abstract's promise of pA/AA/FCC and the pp-only content—is important for scope but does not undermine the pp calculation. The mc unit typo and the 155 vs 155.6 / 107.5 vs 120.62 discrepancies are addressable. The proposed test (gluon veto dependence) would settle whether the NLO calculation is actually exclusive; it could be run by the authors or by an independent group using the same tools (QGRAF/FORM/FIRE/Cuba). The paper has plausible physics and standard NRQCD machinery, so CONDITIONAL is appropriate; my read does not alter the reader's verdict.","tokens_in":9701,"tokens_out":4647,"duration_ms":43226,"concrete_test":"Ask the authors to state and implement the real-gluon phase-space prescription, and recompute the NLO cross section at sqrt(s)=14 TeV with the same inputs (mc, |RS(0)|^2, EDFF flux, b integration) while varying an explicit gluon veto scale, e.g., from 0.1 to 1 GeV. If the exclusive cross section is independent of this veto when the veto → 0, the result is well-defined; if it shifts by a non-negligible amount, the quoted numbers are not the exclusive process.","verdict_should_be":"UNCHANGED","load_bearing_attack":"Section 2 acknowledges UV and IR divergences but never specifies the treatment of real gluon emission in the NLO calculation. The process is advertised as exclusive γγ→J/ψ+γ; an extra gluon in the final state would break exclusivity, while omitting real emission leaves IR poles in virtual corrections without a stated cancellation mechanism. No phase-space definition, soft cut, or veto is given. Consequently, the quoted NLO cross sections (107.5–130 fb) and derived event yields (961–1163) are not uniquely defined. This is the central load-bearing premise: if real emissions are fully integrated, the observable is inclusive; if they are excluded with a cut, the result depends on an unstated parameter. The text's silence on this point makes the headline numbers irreproducible as stated.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper presents an NRQCD-based NLO calculation of exclusive J/ψ+γ production via photon-photon fusion in ultraperipheral proton-proton collisions at √s_NN = 14 TeV, using the electric-dipole form-factor photon flux with explicit impact-parameter dependence and a hadronic survival probability. It reports LO and NLO total cross sections, K-factors for pT>0 and pT>2 GeV, differential pT and rapidity distributions, and expected event yields at the HL-LHC after including the J/ψ→μ+μ− branching fraction. The advertised abstract also claims proton-nucleus and nucleus-nucleus predictions and FCC event yields, but the body of the paper contains only pp results at 14 TeV and HL-LHC luminosities.","tokens_in":9816,"tokens_out":4714,"duration_ms":44652,"significance":"If the NLO calculation is correct, the paper would provide a useful exclusive quarkonium-plus-photon production prediction with a more consistent treatment of the impact-parameter-dependent survival probability than some earlier work. The paper fits no data; all inputs are taken from previous literature, and the LO photon-flux framework is standard. The scale-variation bands and the discussion of the pT dependence are valuable. However, the central NLO claim is not reproducible as written because the treatment of real-gluon emission is never specified, and the published abstract overstates the content of the manuscript.","major_comments":[{"comment":"The NLO calculation is described only by listing renormalization constants. No discussion is given of the real-gluon emission diagrams, their phase-space integration, or how they are reconciled with the exclusive final state γγ→J/ψ+γ. A real gluon in the final state breaks exclusivity; if it is integrated over the observable is inclusive, while if it is vetoed or restricted by a soft cut the result depends on an unstated parameter. The IR poles in the virtual corrections require a specified cancellation mechanism. Since Table 1 and the event yields depend on this choice, the quoted NLO cross sections (107.5–130 fb) are not uniquely defined as written.","section":"§2, Eqs. (6)–(9)"},{"comment":"The abstract states that the study covers proton-proton, proton-nucleus, and nucleus-nucleus collisions with nuclear species O, Ca, Ar, Kr, Xe, and Pb at both HL-LHC and FCC, and that event yields are given for the FCC. Section 3 contains only pp collisions at √s=14 TeV and event yields for the HL-LHC. No pA, AA, or FCC results appear anywhere in the text. The title also advertises 'proton and nuclear collisions'. This is a major scope mismatch that must be corrected, either by adding the missing results or by revising the abstract and title to match the actual content.","section":"Abstract vs. §3"},{"comment":"The conclusion states that NLO corrections reduce the cross section from 155 fb to 107.5 fb. In Table 1, the NLO cross section for pT>0 ranges from 107.49 to 130.09 fb, with the central value at μr=√(4m_c²+pT²) equal to 120.62 fb and the value 107.5 corresponding to the lower edge of the scale variation. The conclusion should quote the central value or explicitly identify 107.5 fb as a scale-variation endpoint, not as the representative NLO result. The abstract's 'between 107.5 fb and 130 fb' is acceptable as a range, but the conclusion's phrasing is misleading.","section":"§4 Conclusion vs. Table 1"},{"comment":"Equation (11) gives the charm quark mass as m_c = 1.5 MeV. This is three orders of magnitude smaller than the value used in the numerical calculation; evidently GeV is intended. Because m_c enters the phase space and the renormalization constants, this typo is confusing and should be corrected.","section":"§3, Eq. (11)"}],"minor_comments":[{"comment":"The caption text 'NLO with scale /uni03BC μ uncertainty' contains a garbled Unicode escape; it should simply say 'NLO with scale μ uncertainty'. Similar artifacts appear in the label of Fig. 2.","section":"Fig. 1 caption"},{"comment":"Reference [16] is incomplete: it gives a title and year but no journal, volume, pages, or arXiv number. Several other references also lack full bibliographic data (e.g., [20], [21], [22]). The authors should ensure all references are complete.","section":"References"},{"comment":"The survival probability is written as Pnoinel in Eq. (3) but P_noinel in Eq. (4) and in the text. Use a single notation consistently.","section":"Notation"}],"recommendation":"major_revision","confidential_remarks":"The gap between the advertised abstract and the actual content is severe enough that the editor should verify which version is intended for submission. The more substantive technical issue is the complete absence of a description of the NLO real-gluon phase space in an exclusive process; without it, the cross-section numbers are not reproducible. The authors should be asked to provide the derivation, or at least a precise statement of the phase-space cuts and IR-cancellation scheme, before the paper can be considered further. The mc unit typo also suggests the manuscript needs a careful proofreading pass."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"The new thing here is the inclusion of an impact-parameter-dependent survival probability in an NLO calculation of gamma-gamma to J/psi + gamma in pp UPCs. That is a real improvement over Ref. [41], which set P_noinel = 1. The paper also gives a clear look at the pT dependence of the K-factor and the scale uncertainty, and the authors are upfront about the standard tools they used. No data are fitted, so the central result is not circular.\n\nThe soft spots are real. The most serious is that the NLO phase space is not defined. The paper says they encountered UV and IR divergences and renormalized, but never states whether real-gluon emission is included, excluded, or restricted by a cut. In an exclusive process, an extra gluon in the final state breaks the exclusivity, so you need at least a soft-gluon veto or an explicit demonstration that real emissions vanish. Without that, the quoted cross sections and event yields are not uniquely defined. This is load-bearing, not a cosmetic detail.\n\nSecond, the abstract promises pA and AA predictions and FCC numbers, but the body only delivers pp at 14 TeV. That is an overclaim. Third, the conclusion quotes 107.5 fb as the NLO result, but the central scale is 120.62 fb; 107.5 is the lower edge of the scale band. That is misleading. Fourth, Eq. (11) has mc = 1.5 MeV instead of GeV — obviously a typo, but the kind that makes a reader distrust all the inputs.\n\nThe NLO derivation itself is not shown; the authors briefly list the packages they used and the renormalization constants. That is acceptable if the result is an incremental extension of known machinery, but given the missing real-emission treatment, it leaves too much unverifiable.\n\nDespite these issues, the central physics is plausible. The b-dependent survival probability is a legitimate improvement, and the process is a sensible observable for HL-LHC. The errors are fixable in a revision. I would send this to a serious referee, but not accept it as is. The referee should ask for the phase-space definition, a corrected abstract, and a consistent set of numbers. This paper is most useful to people actively working on UPC quarkonium production and NRQCD predictions; for them it is worth a read, but it is not a paper I would cite for its numbers until the details are sorted out.","headline":"Plausible NLO update with a real new element (b-dependent survival probability), but the NLO real-gluon phase space is undefined and the abstract overclaims the scope; deserves a rigorous referee.","tokens_in":10399,"tokens_out":2677,"would_cite":false,"duration_ms":25462,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"NLO QCD corrections suppress exclusive J/ψ+γ production, but the channel stays observable at the HL-LHC.","keywords":["NRQCD","charmonium","J/psi production","ultraperipheral collisions","photon-photon fusion","NLO QCD corrections","impact parameter","HL-LHC"],"falsifier":"Recompute the NLO cross section with an explicit definition of the real-emission phase space (for example, a gluon energy cutoff) for pT>2 GeV; if the result falls outside the quoted 6.31–10.25 fb range, the paper's central numbers are not reproducible under a different but equally plausible exclusivity prescription. Experimentally, an HL-LHC measurement of the exclusive J/ψ+γ cross section with pT>2 GeV that disagrees with the predicted range by more than the scale variation would likewise falsify the calculation.","tokens_in":9499,"feed_emoji":"⚛️","tokens_out":8537,"duration_ms":65011,"temperature":0.7,"pith_summary":"The paper argues that exclusive J/ψ+γ production via photon-photon fusion in proton-proton ultraperipheral collisions is a viable observable at the High-Luminosity LHC. It presents an NRQCD-based NLO calculation that reduces the leading-order cross section of 155 fb to 107–130 fb (K-factor 0.69–0.82) for pT>0, and to 6–10 fb (K-factor 0.43–0.65) when a pT>2 GeV cut is applied. The calculation explicitly retains the impact-parameter dependence of the photon fluxes, which enforces the exclusivity of the final state and lowers the rate relative to earlier estimates. The authors conclude that with 150 fb−1 of data and the J/ψ→μ+μ− branching ratio, the HL-LHC should record roughly a thousand signal events, making the process a sensitive probe of charmonium photoproduction mechanisms.","feed_headline":"NLO corrections cut J/ψ+γ rate, yet ~1000 events survive at HL-LHC","feed_subtitle":"NRQCD NLO predicts 107–130 fb in pp UPCs; with 150 fb−1, ~1000 J/ψ→μμ events expected.","key_machinery":"The central object is the NRQCD factorization formula dσ = ∫dEγ1/Eγ1 dEγ2/Eγ2 d²N(γ1,γ2)/dEγ1dEγ2 × dσ̂(γγ→c̄c[3S1[1]]+γ) × ⟨O[J/ψ]⟩, where the photon number densities are obtained from the electric-dipole form factor and carry an explicit dependence on the impact parameter b. The flux convolution includes the hadronic survival probability P_noinel(|b1−b2|), which suppresses events with additional inelastic hadronic interactions and thereby enforces the exclusive final state. The NLO short-distance coefficients are computed with dimensional regularization, on-shell renormalization for the charm-quark wave function and mass, and MS renormalization for the strong coupling; the authors emphasiz","core_discovery":"Within the NRQCD factorization framework, taking the charm–anticharm pair in the color-singlet 3S1[1] channel and modeling the proton's photon flux with the electric-dipole form factor while explicitly integrating over impact parameter, the exclusive γγ→J/ψ+γ cross section at 14 TeV pp UPCs is predicted to be 155 fb at leading order. Including NLO QCD corrections renormalized in the on-shell and MS schemes yields 107.5–130.1 fb for pT>0 (central 120.6 fb) and 6.31–10.25 fb for pT>2 GeV, corresponding to K-factors of 0.69–0.82 and 0.43–0.65, respectively. These numbers, after accounting for the 5.961% J/ψ→μ+μ− branching ratio, translate into 961–1163 expected signal events at the HL-LHC with","pith_inferences":["The paper's conclusions extend naturally to nuclear UPCs (O, Ca, Ar, Kr, Xe, Pb) as announced in the title and abstract, but the numerical results in this version are limited to proton–proton collisions; the nuclear predictions would be a straightforward extension of the same machinery.","A decisive test of the exclusivity assumption would be to compute the NLO cross section with a soft-gluon cutoff; if the result moves outside the quoted scale-variation band, the unstated real-emission phase-space definition is the main source of uncertainty.","Measuring the ratio of cross sections with pT>2 GeV and pT>0 would isolate the NLO suppression pattern from normalization uncertainties, since the predicted ratio changes by roughly a quarter relative to LO."],"forward_implications":["If the NLO prediction is right, the exclusive J/ψ+γ channel will be measurable at the HL-LHC with approximately one thousand clean dimuon events, enough for first differential pT and rapidity studies.","The K-factor decreases steeply with the pT cut (0.69–0.82 for pT>0 versus 0.43–0.65 for pT>2 GeV), indicating that perturbative convergence worsens at high pT and that NNLO corrections will be needed for precision comparisons.","Because the impact-parameter-dependent flux lowers the cross section relative to calculations that assume a 100% survival probability, any data-theory comparison must use the b-dependent treatment to be meaningful.","The predicted NLO suppression in the central rapidity region (|y|<2) provides a qualitative feature that can be checked directly with the HL-LHC forward-detector data."],"fun_headline_variants":["Ultraperipheral J/ψ+γ: NLO predicts 961–1163 events at HL-LHC","Exclusive J/ψ+γ: NLO cuts cross section, yet 1000 events remain","J/ψ+γ from UPCs: NLO predicts 107–130 fb, 961–1163 events","Exclusive photon fusion J/ψ+γ: NLO yields ~1000 events at HL-LHC","NLO reduces J/ψ+γ rate by 35%, but ~1000 events remain"],"cache_read_input_tokens":2304,"weakest_assumption_plain":"The NLO cross-section numbers rest on an unspecified treatment of real-gluon emission: the process must remain exclusive, so any emitted gluon must be absent or soft, but the paper does not state how that constraint is implemented or how infrared divergences cancel under it.","fun_headline_variants_meta":{"raw":{"variants":["Ultraperipheral J/ψ+γ: NLO predicts 961–1163 events at HL-LHC","Exclusive J/ψ+γ: NLO cuts cross section, yet 1000 events remain","J/ψ+γ from UPCs: NLO predicts 107–130 fb, 961–1163 events","Exclusive photon fusion J/ψ+γ: NLO yields ~1000 events at HL-LHC","NLO reduces J/ψ+γ rate by 35%, but ~1000 events remain"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.001212,"raw_usage":{"total_tokens":4891,"prompt_tokens":877,"completion_tokens":4014,"prompt_tokens_details":{"cached_tokens":256},"prompt_cache_hit_tokens":256,"prompt_cache_miss_tokens":621,"completion_tokens_details":{"reasoning_tokens":3881}},"tokens_in":621,"tokens_out":4014,"duration_ms":25748,"temperature":1.0,"reasoning_tokens":3881,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-04T10:17:13.551115+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Recompute the NLO cross section with an explicit definition of the real-emission phase space (for example, a gluon energy cutoff) for pT>2 GeV; if the result falls outside the quoted 6.31–10.25 fb range, the paper's central numbers are not reproducible under a different but equally plausible exclusivity prescription. Experimentally, an HL-LHC measurement of the exclusive J/ψ+γ cross section with pT>2 GeV that disagrees with the predicted range by more than the scale variation would likewise falsify the calculation.","supporting_citations":[],"review_version":1}