{"id":"f76674ab-502d-4c48-aeb3-319d5b9a5e0e","arxiv_id":"2505.13892","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":5.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":0,"one_line_summary":"New Run 3 ALICE measurements of J/psi and Upsilon(1S) elliptic flow in Pb-Pb collisions at 5.36 TeV, including the first J/psi v2{4} result, are presented.","lead":"ALICE measured how quarkonium particles flow in lead-lead collisions at a new energy, using three different analysis methods. The results, including a first multi-particle cumulant measurement, put new constraints on models of the quark-gluon plasma.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The 2.7σ deficit of v2{4} relative to v2{SP} is the only evidence for the claimed new sensitivity to J/psi flow fluctuations, and its interpretation requires Gaussian fluctuations and non-flow suppression that the paper neither verifies nor quantifies.","rationale":"The reader's verdict (CONDITIONAL, medium correctness risk) is appropriate. The paper's new Run 3 J/psi v2 measurements have independent value as preliminary data, and agreement with Run 2 plus the plausible hierarchy v2(J/psi) < v2(D0) < v2(Lambda_c) is consistent with the thermalization picture. I agree with the reader that the weakest assumption is in the 2.7σ fluctuation claim, not in the basic v2 measurement. My stress-test sharpens this: the claim is not merely overstated; it is underdetermined by the presented material. The agreement among EP, SP and v2{2} is used to validate the observed anisotropy, but those methods share two-particle non-flow sensitivity and use different reference detectors, so agreement cannot certify the fluctuation interpretation. Moreover, Eq. (2) is applied to J/psi with one forward muon probe, where the standard cumulant denominator and the amount of self-correlation differ from inclusive hadron measurements. A 2.7σ statistical deficit without systematic error bars is not enough to claim strong sensitivity to fluctuations. Since the reader already conditioned acceptance on releasing data and tempering or testing the interpretation, I do not change the verdict. If the proposed three-subevent test shows the deficit persists, the claim would become much stronger; if not, the conclusion should be dropped. The manuscript itself notes where uncertainties preclude firm conclusions for Upsilon, showing the authors are capable of cautious statements, which makes the strong fluctuation wording for a 2.7σ effect particularly in need of support.","tokens_in":4129,"tokens_out":6592,"duration_ms":64529,"concrete_test":"Re-analyze the same 10–30% sample using a three-subevent cumulant c2{4|3} in which the J/psi is measured in the forward muon arm and the three reference particles are required to come from two distinct midrapidity subevents separated by an additional eta gap; compare the resulting v2{4} with the reported v2{4} and v2{SP}. If the deficit v2{SP}-v2{4} drops below 2σ or changes sign under this non-flow-suppressed estimator, the flow-fluctuation interpretation is not supported. As a cross-check, run the same estimator on the 50–80% centrality class and on a low-pT bin where quarkonium flow is expected small; a nonzero deficit there would indicate residual method bias.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The paper's headline new result is not the positive J/psi v2 (which agrees with Run 2) but the first sensitivity to J/psi flow fluctuations, inferred from a 2.7σ deficit v2{4} < v2{SP} in 10–30% Pb–Pb (Fig. 3, Eq. 2). This inference is load-bearing because without it the paper offers no new physics claim beyond confirming Run 2. The inference requires that (i) v2{SP}, v2{EP} and v2{2} all measure the same two-particle flow with negligible non-flow, and (ii) event-by-event fluctuations of J/psi flow are Gaussian so Eq. (1) and Eq. (2) apply. The paper provides no evidence for either. Agreement among EP/SP/v2{2} is not evidence: those are all two-particle methods, and the SP/EP reference particles (FT0 forward detectors) differ from the midrapidity charged particles used for v2{2} and v2{4}, so they can carry different non-flow and resolution corrections. The |Delta eta|>1.7 gap suppresses short-range correlations but does not remove long-range dijet or momentum-conservation correlations, and the J/psi itself is a hard probe whose production may correlate with the reference charged particles. Since the quoted significance is statistical and no systematic uncertainties or data tables are given, the 2.7σ deficit could be a method difference rather than flow fluctuations.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"This ALICE preliminary proceedings paper reports new Run 3 Pb-Pb measurements at sqrt(s_NN)=5.36 TeV of J/psi elliptic flow at forward rapidity (2.5<y<4) using event-plane, scalar-product, and, for the first time, multiparticle cumulant methods, together with a first Upsilon(1S) v2 measurement. The J/psi v2{SP} centrality and pT dependence is found consistent with Run 2. The new quantitative claim is a 2.7 sigma deficit of v2{4} relative to v2{SP} in 10-30% centrality, which the paper interprets as the first strong sensitivity to J/psi flow fluctuations under a Gaussian fluctuation assumption. The Upsilon(1S) v2 is consistent with zero and is compared qualitatively with the TAMU and BBJS models.","tokens_in":4430,"tokens_out":3188,"duration_ms":30635,"significance":"If the central fluctuation claim survives scrutiny, the paper would provide the first experimental indication of event-by-event fluctuations in quarkonium elliptic flow, a genuinely new constraint on quarkonium production and thermalization in the quark-gluon plasma. The comparison of J/psi, Upsilon(1S), and open heavy-flavour v2 values across rapidity also adds useful model discrimination. The paper is strengthened by the use of multiple independent flow methods, explicit statistical and systematic uncertainty bars on the figures, and direct comparison to published theoretical models without introducing free parameters or fitting model parameters.","major_comments":[{"comment":"The paper's central new claim, the first sensitivity to J/psi flow fluctuations, rests entirely on the 2.7 sigma deficit of v2{4} relative to v2{SP} in the 10-30% centrality class. This interpretation requires two unverified assumptions: (i) that event-by-event elliptic flow fluctuations are Gaussian so that Eqs. (1)-(2) apply, and (ii) that the |Delta eta| > 1.7 gap removes all relevant non-flow correlations. The paper provides no test of Gaussianity and no quantification of residual non-flow. The reference particles for v2{SP} and v2{EP} (FT0 forward detectors) differ from the midrapidity charged particles used for v2{2} and v2{4}, so the two sets can carry different non-flow and resolution corrections. Since the quoted 2.7 sigma is statistical, the observed deficit could be a method difference rather than a flow-fluctuation signal. I ask the authors to quantify or otherwise bound these effects before making the fluctuation claim.","section":"Results, Fig. 3"},{"comment":"The systematic uncertainties shown in the figures are never defined. The paper does not describe how the systematic uncertainties were estimated, how the event-mixing normalization was performed, or how the event-plane resolution correction was applied to the v2{EP} and v2{SP} results. More importantly, no systematic uncertainty is quoted for the 2.7 sigma significance of v2{4} < v2{SP}, and no correlation between the v2{4} and v2{SP} systematic uncertainties is given. Without this information the reader cannot evaluate whether the central deficit is robust. A short description of the systematic procedure and a table of results with combined uncertainties would resolve this.","section":"Results, Fig. 3"},{"comment":"Equation (2) as written is dimensionally inconsistent: it states v2{4} = <v2>^2 - sigma_v^2, whereas the left-hand side is a flow coefficient and the right-hand side has dimensions of squared flow. The standard relation is v2{4}^2 = <v2>^2 - sigma_v^2. If the authors intend v2{4} to denote the squared quantity, this should be stated explicitly; otherwise the formula is a technical error that obscures the fluctuation interpretation.","section":"Results, Eq. (2)"}],"minor_comments":[{"comment":"The left panel legend lists centrality classes 10-30% and 30-50%, while the caption says the panel shows 0-10%, 10-30%, and 30-50%; please make the legend and caption consistent.","section":"Results, Fig. 2"},{"comment":"The right panel caption contains an garbled pT range ('c < 15 GeV/Tp') and the left panel caption also has formatting issues; please correct these to the intended 'pT < 15 GeV/c' and '2.5 < y < 4'.","section":"Results, Fig. 4"},{"comment":"The phrase 'a strong sensitivity to J/psi flow fluctuations' is stronger than a 2.7 sigma statistical deficit warrants; the authors may wish to soften this to 'first evidence' or 'first indication' unless a full systematic treatment changes the significance.","section":"Results, p. 3"},{"comment":"Reference 2 combines a 2008 JINST detector paper with a 2023 arXiv identifier that appears unrelated; please verify the citation and provide the correct arXiv number for the ALICE detector description.","section":"References"}],"recommendation":"major_revision","confidential_remarks":"This is a short preliminary proceedings contribution. The central fluctuation claim is potentially interesting but is supported only by a statistical significance with unquantified systematics and an unverified Gaussianity assumption. I recommend major revision so that the authors either supply the missing systematic and methodological details or appropriately qualify the claim."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Hi [colleague],\n\nShort version: this is a solid preliminary measurement paper, not a discovery. The genuinely new items are first Run 3 Pb–Pb quarkonium flow at 5.36 TeV, first J/ψ v2{4} from multi-particle cumulants, and a new 50–80% centrality point for J/ψ v2{EP}. The measured J/ψ v2 is consistent with Run 2, which is a useful cross-check and improves centrality granularity. The SP/EP/v2{2} agreement in Fig. 3 is reassuring, and the Υ(1S) v2 being consistent with zero matches the low regeneration expectation. The comparison to TAMU and BBJS is qualitative but appropriate for a proceedings contribution.\n\nWhere I part company with the paper's own framing is the “first strong sensitivity to J/ψ flow fluctuations” claim. That claim rests entirely on a 2.7σ deficit of v2{4} relative to v2{SP} in one centrality class. To interpret that deficit as flow fluctuations, you need Eq. (1)–(2), which assume Gaussian event-by-event fluctuations, and you need to know that the reference particles for SP/EP and the midrapidity charged particles for v2{2}/v2{4} all carry the same non-flow content. The |Δη|>1.7 gap suppresses short-range correlations but does not kill long-range dijet or momentum-conservation correlations, and J/ψ production can itself correlate with reference particles. The paper does not supply systematic uncertainties for the cumulant points, nor data tables, nor a check of the Gaussian assumption. So the 2.7σ deficit could be a method difference. That does not make the measurement wrong, but it makes the headline claim unproven.\n\nThe other soft spots are the standard “preliminary conference report” kind: no event-mixing normalization details, no discussion of event-plane resolution corrections or systematic estimation. I would not refuse to publish it on those grounds — it is a proceedings-style paper. The citations are standard and appropriately placed.\n\nBottom line: who is this for? Heavy-ion phenomenologists who want the new 5.36 TeV J/ψ and Υ(1S) flow points, and experimentalists tracking ALICE Run 3 output. It deserves a sober referee, but the referee should insist that the fluctuation language be tempered to “a 2.7σ deficit consistent with, but not yet establishing, flow fluctuations” and that data tables be released. As it stands, the conclusion outruns the evidence, but the data are worth having.\n\nRecommendation: send to peer review, with a request for a revised claim and accompanying numerical tables.","headline":"The new Run 3 quarkonium v2 data are genuinely useful, but the paper's only new physics claim — a 2.7σ sensitivity to J/ψ flow fluctuations — is load-bearing and not yet supported by the analysis details.","tokens_in":4937,"tokens_out":2736,"would_cite":true,"duration_ms":26810,"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":"This paper reports the first quarkonium elliptic-flow measurements from 5.36 TeV Pb–Pb collisions, including a 2.7σ deficit of the four-particle cumulant that may signal event-by-event J/ψ flow fluctuations.","keywords":["quarkonium","elliptic flow","heavy-ion collisions","quark-gluon plasma","J/psi","Upsilon","cumulants","Run 3"],"falsifier":"A measurement with larger statistics that does not reproduce the $v_2\\{4\\}$ deficit in a given centrality or $p_T$ bin, or a demonstration that residual non-flow survives the $|\\Delta\\eta|>1.7$ gap, would falsify the claim of strong sensitivity to $J/\\psi$ flow fluctuations.","tokens_in":1866,"feed_emoji":"⚫","tokens_out":6734,"duration_ms":108514,"temperature":0.7,"pith_summary":"This paper reports new measurements of quarkonium elliptic flow ($v_2$) in lead–lead collisions at $\\sqrt{s_{NN}}=5.36$ TeV using the 2023 Run 3 dataset. It finds a positive $J/\\psi$ $v_2$ across a broad transverse-momentum range, consistent with earlier runs, and reports a $2.7\\sigma$ deficit of the four-particle cumulant $v_2\\{4\\}$ relative to the scalar-product $v_2\\{SP\\}$, which the paper interprets as the first strong sensitivity to event-by-event fluctuations of $J/\\psi$ flow. The $\\Upsilon(1S)$ $v_2$ is consistent with zero, as expected if bottom-quark regeneration is rare. These measurements constrain how fully charm and beauty quarks thermalize and recombine in the quark-gluon plasma.","feed_headline":"J/psi flow shows first 2.7-sigma fluctuation signal","feed_subtitle":"New 5.36 TeV Pb-Pb quarkonium flow data test charm and beauty thermalization in the QGP.","key_machinery":"The central objects are Fourier flow harmonics $v_2\\{EP\\}$, $v_2\\{SP\\}$, $v_2\\{2\\}$, and $v_2\\{4\\}$, extracted from azimuthal correlations between dimuons at forward rapidity and charged particles or the event plane. The multi-particle cumulant technique, applied here for the first time to $J/\\psi$ flow, provides the new $v_2\\{2\\}$ and $v_2\\{4\\}$ observables. The interpretative machinery is the Gaussian-fluctuation assumption that relates $v_2\\{SP\\}^2$ and $v_2\\{4\\}^2$ to the mean flow $\\langle v_2\\rangle$ and its event-by-event variance $\\sigma_v^2$; the observed $v_2\\{4\\}<v_2\\{SP\\}$ deficit is what carries the claim of sensitivity to $J/\\psi$ flow fluctuations.","core_discovery":"The central claim is that quarkonia participate in the collective flow of the quark-gluon plasma to a degree that can now be quantified with Run 3 statistics. The $J/\\psi$ elliptic flow measured by the event-plane, scalar-product, and two-particle cumulant methods agree with one another and with Run 2 results, establishing a positive anisotropy from $p_T=0$ up to about 10 GeV/$c$ in several centrality classes. The new four-particle cumulant result lies below $v_2\\{SP\\}$ with $2.7\\sigma$ significance, which the paper takes, under the assumption of Gaussian flow fluctuations, as evidence for event-by-event fluctuations in $J/\\psi$ flow. The $\\Upsilon(1S)$ measurement is compatible with zero and is compared with two theoretical models; the data agree qualitatively but cannot yet distinguish the models.","pith_inferences":["The same cumulant comparison could be made for charged hadrons in the same events; the ratio of the inferred flow variance for $J/\\psi$ to that for light hadrons would test whether heavy quarks inherit the full medium fluctuation spectrum or are diluted by their hard-production vertex.","If the $v_2\\{4\\}$ deficit grows with centrality in the same way as initial-state eccentricity fluctuations, it would support a hydrodynamic origin; if it is centrality-independent, it would favour initial-state correlation mechanisms of the kind the paper cites.","A future $\\Upsilon$ $v_2\\{4\\}$ measurement with the same technique could sharpen the contrast between the near-zero $\\Upsilon$ $v_2$ and the positive $J/\\psi$ signal, testing whether bottom quarks are merely less thermalized or also less fluctuating."],"forward_implications":["If the $2.7\\sigma$ deficit is real, higher-statistics Run 3 data will map $J/\\psi$ flow fluctuations as a function of centrality and $p_T$.","The cross-method agreement among $v_2\\{EP\\}$, $v_2\\{SP\\}$, and $v_2\\{2\\}$ indicates that the observed $J/\\psi$ anisotropy is not an artifact of a single extraction method.","The positive low-$p_T$ $J/\\psi$ $v_2$ strengthens the regeneration scenario for charmonium in the quark-gluon plasma and will tighten model constraints on charm-quark diffusion and recombination.","The $\\Upsilon(1S)$ $v_2$ being consistent with zero constrains beauty-quark thermalization and bottomonium regeneration, even if current uncertainties do not allow firm conclusions."],"supporting_citations":[{"why":"This reference defines elliptic flow as the second Fourier harmonic of the azimuthal distribution of produced particles.","marker":"[1]"},{"why":"This reference describes the ALICE apparatus used to detect dimuons at forward rapidity and to measure the event plane.","marker":"[2]"},{"why":"This reference supplies the regeneration scenario used to explain the positive low-$p_T$ $J/\\psi$ $v_2$.","marker":"[3]"},{"why":"This reference provides the multi-particle cumulant formalism used for the first $v_2\\{2\\}$ and $v_2\\{4\\}$ extraction.","marker":"[4]"},{"why":"This reference gives the Gaussian-fluctuation relations connecting $v_2\\{SP\\}$, $v_2\\{2\\}$, and $v_2\\{4\\}$ that underlie the $2.7\\sigma$ deficit interpretation.","marker":"[5]"},{"why":"This reference provides the hydrodynamic rate-equation quarkonium model used for comparison to the $\\Upsilon(1S)$ $v_2$ data.","marker":"[6]"},{"why":"This reference provides the Schrodinger-Langevin quarkonium model used as the second comparison for the $\\Upsilon(1S)$ $v_2$ data.","marker":"[7]"},{"why":"This reference supplies the initial-state correlation framework that predicts flow-like effects, cited as an alternative to hydrodynamic thermalization.","marker":"[8]"}],"fun_headline_variants":["Quarkonia flow: first 2.7-sigma fluctuation signal","J/psi elliptic flow shows 2.7-sigma fluctuation","Run 3 Pb-Pb data: quarkonia flow in QGP","Upsilon and J/psi flow: new LHC constraints","Quarkonium collectivity: four-particle cumulant dip"],"cache_read_input_tokens":7040,"weakest_assumption_plain":"The interpretation of the observed $v_2\\{4\\}<v_2\\{SP\\}$ deficit as flow fluctuations depends on the assumption that event-by-event elliptic flow is Gaussian-distributed and that the $|\\Delta\\eta|>1.7$ gap removes all non-flow contributions; if either fails, the central claim collapses.","fun_headline_variants_meta":{"raw":{"variants":["Quarkonia flow: first 2.7-sigma fluctuation signal","J/psi elliptic flow shows 2.7-sigma fluctuation","Run 3 Pb-Pb data: quarkonia flow in QGP","Upsilon and J/psi flow: new LHC constraints","Quarkonium collectivity: four-particle cumulant dip"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000348,"raw_usage":{"total_tokens":1880,"prompt_tokens":898,"completion_tokens":982,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":514,"completion_tokens_details":{"reasoning_tokens":892}},"tokens_in":514,"tokens_out":982,"duration_ms":8581,"temperature":1.0,"reasoning_tokens":892,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-15T20:07:26.515033+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"A measurement with larger statistics that does not reproduce the $v_2\\{4\\}$ deficit in a given centrality or $p_T$ bin, or a demonstration that residual non-flow survives the $|\\Delta\\eta|>1.7$ gap, would falsify the claim of strong sensitivity to $J/\\psi$ flow fluctuations.","supporting_citations":[{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"This reference defines elliptic flow as the second Fourier harmonic of the azimuthal distribution of produced particles."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"This reference provides the hydrodynamic rate-equation quarkonium model used for comparison to the $\\Upsilon(1S)$ $v_2$ data."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"This reference provides the Schrodinger-Langevin quarkonium model used as the second comparison for the $\\Upsilon(1S)$ $v_2$ data."}],"review_version":1}