{"id":"b197baaf-7c42-43e1-8e03-53b0534639cd","arxiv_id":"2607.13758","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":0,"one_line_summary":"First evidence of sequential Upsilon(nS) suppression in oxygen-oxygen and neon-neon collisions, with the Upsilon(3S)/Upsilon(2S) ratio reduced by 3.2 standard deviations.","lead":"This paper reports the first measurements of Upsilon(1S), Upsilon(2S), and Upsilon(3S) mesons in oxygen-oxygen collisions, and Upsilon(1S,2S) in neon-neon collisions, at the LHC. The excited states are suppressed relative to the ground state by several standard deviations, providing evidence that quark-gluon plasma effects can appear in small collision systems.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Central claim rests on unverified assumption that cold-nuclear-matter effects are state-independent; if false, OO/NeNe double ratios could mimic sequential final-state suppression.","rationale":"The reader's weakest assumption identified the same load-bearing point: cancellation of cold-nuclear-matter effects assumes state-independence. I agree, and I would keep the verdict CONDITIONAL rather than ACCEPT because the paper's headline evidence—especially the 3.2-sigma D32—does not by itself exclude state-dependent CNM. The NeNe D21=0.27 being lower than OO is notable, but it is not the most decisive issue: it could still be consistent with a larger average Npart for NeNe, and it would reinforce suppression rather than undermine it if the system-size ordering is as stated. The central fragility is that the D_nm construction is asserted to cancel initial-state effects without a dedicated calculation or a relevant citation. The paper is a careful measurement with plausible systematic handling, so this is not grounds for rejection; it is grounds for demanding a specific CNM test before the 'first evidence for sequential suppression' is read as evidence for QGP-like final-state effects. My proposed CNM-only calculation would settle whether the concern actually lands, and it can be done with existing nPDF and energy-loss frameworks.","tokens_in":34446,"tokens_out":9924,"duration_ms":110926,"concrete_test":"Run a dedicated CNM-only calculation for OO and NeNe at sqrt(s_NN)=5.36 TeV using the paper's acceptance (pT<30 GeV, |y|<2.4) and the same feed-down assumptions, with state-dependent nPDFs and coherent energy loss for the 1S, 2S, and 3S states. Compare the predicted D21, D31, and D32 to the measured 0.664, 0.392, and 0.59. If the CNM-only prediction reproduces D32 around 0.59 within uncertainties, the final-state sequential-suppression claim is not established; if it predicts D32 compatible with unity, the concern is retired.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The paper's central inference that D21=0.664, D31=0.392, and D32=0.59 in OO constitute evidence for sequential final-state suppression depends on the assertion in the paragraph defining D_nm: initial-state nuclear effects are 'expected to modify all of the Upsilon(nS) states similarly.' That is the load-bearing premise. D_nm is a ratio of inclusive excited-to-ground yields in AA divided by the same in pp, so any state-dependent cold-nuclear-matter (CNM) modification—nPDF shadowing/anti-shadowing, coherent energy loss, Cronin broadening, or state-dependent feed-down—survives in D_nm. The paper provides no quantitative support for state-independence. The citation attached to the assumption, [49], concerns coherent Upsilon(1S) photoproduction, not hadroproduction CNM, so it does not address the premise. The text itself later acknowledges 'possible differences in feed-down contributions' when comparing systems. Moreover, the D32 deficit—the specific new evidence for sequential suppression—is only 3.2 sigma, so a modest state-dependent CNM correction could move it to unity. The SHINCHON comparison does not resolve this: it contains no CNM and significantly underestimates the measured suppression, leaving room for a CNM contribution of roughly the needed size. Thus the observation that the ratios fall below unity is robust, but the claim that they isolate QGP-like final-state sequential suppression is not.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The manuscript reports the first measurements of the Upsilon(1S), Upsilon(2S), and Upsilon(3S) states in oxygen-oxygen collisions and of the Upsilon(1S,2S) states in neon-neon collisions at sqrt(s_NN)=5.36 TeV, using a pp reference at the same energy. The analysis is based on dimuon invariant mass fits, acceptance/efficiency corrections, and standard systematic variations. The central results are the double ratios D21=0.664+/-0.055+/-0.007, D31=0.392+/-0.077+/-0.023, and D32=0.59+/-0.12+/-0.04 in OO, and D21=0.27+/-0.12+/-0.01 in NeNe. The paper interprets the OO ratios, especially the 3.2-sigma D32 deficit, as evidence for sequential Upsilon(nS) suppression in small symmetric collision systems, compares the results with pPb and PbPb measurements and with the SHINCHON model, and reports multiplicity and pT differential trends.","tokens_in":34804,"tokens_out":10183,"duration_ms":92525,"significance":"If the interpretation holds, the OO D32 deficit is the first indication that Upsilon(3S) is suppressed relative to Upsilon(2S) in light-ion collisions, extending the sequential-suppression pattern to systems with Npart of order 10. The experimental analysis is careful, the values are stated with separated statistical and systematic uncertainties, and the quoted significances are internally consistent with the reported numbers: D21 is about 6.1 sigma, D31 about 7.6 sigma, and D32 about 3.2 sigma below unity. The paper is appropriately cautious in calling D32 'evidence' rather than 'observation.' The primary weakness is that the final-state interpretation rests on the premise that initial-state nuclear effects cancel in D_nm because they affect all Upsilon(nS) states similarly; this premise is not quantitatively supported and is load-bearing for the central claim.","major_comments":[{"comment":"The statement that D_nm and S_nm cancel initial-state nuclear effects 'expected to modify all of the Upsilon(nS) states similarly [49]' is load-bearing for the conclusion. Reference [49] is a coherent-photoproduction measurement and does not address hadroproduction cold-nuclear-matter effects. nPDF shadowing/anti-shadowing, coherent energy loss, and state-dependent feed-down can leave a state-dependent contribution in D_nm. The paper itself later, in the multiplicity paragraph, acknowledges 'possible differences in feed-down contributions.' Since D32 is only 3.2 sigma from unity, a modest state-dependent CNM correction could move it to unity. Please provide a quantitative bound on state-dependent CNM (e.g., from pPb double ratios or nPDF calculations) or explicitly weaken the final-state conclusion.","section":"Section 2, D_nm definition"},{"comment":"The SHINCHON comparison is invoked as support for a final-state interpretation, but the model description given in the text contains no CNM component. The paper states that the calculation 'significantly underestimates the measured suppression,' but the gap is of the same order as the size of a CNM contribution that would be needed to explain the data. This comparison therefore does not close the loophole identified in the D_nm definition. The summary statement that these observables 'isolate final-state medium effects' is too strong. The manuscript should either add state-dependent CNM to the model comparison or state that the data are consistent with, but do not uniquely require, QGP-driven sequential suppression.","section":"Figure 3 / SHINCHON comparison"},{"comment":"The measured NeNe D21 = 0.27 +/- 0.12 +/- 0.01 is quoted as 3.0 standard deviations lower than the OO D21 = 0.664. This is a striking difference between two small symmetric systems and is not discussed beyond the quoted significance. If taken at face value it complicates the 'clear hierarchy' in Fig. 2 and the system-size narrative. The authors should quantify the consistency between OO and NeNe with correlated systematics treated explicitly, and discuss whether the difference bears on the state-independence assumption for CNM effects.","section":"Results, NeNe D21"}],"minor_comments":[{"comment":"The abstract says 'The Upsilon(2S)/Upsilon(1S) ratio is found to be significantly below the measured pp reference value' without specifying the collision system. Since the OO and NeNe values differ substantially, this should be made explicit for both systems.","section":"Abstract"},{"comment":"The text says the right panel presents pT-differential D21, D31, and D32, but the figure caption only names D32. Please make the caption consistent with the content of the panel.","section":"Figure 3 caption"},{"comment":"The systematic uncertainty ranges are useful, but a compact table listing all integrated and differential D_nm and S_nm values with statistical and systematic uncertainties would improve readability and reproducibility.","section":"Systematics paragraph"},{"comment":"The 3.0-standard-deviation difference between NeNe and OO D21 should state explicitly how the uncertainty was combined (statistical and systematic, with or without correlations between the two measurements) so that the claim is reproducible.","section":"NeNe significance"}],"recommendation":"major_revision","confidential_remarks":"This is a valuable measurement with a sound statistical core. My main concern is that the central interpretational claim, that the observed double-ratio deficits constitute evidence for sequential final-state suppression, depends on an unquantified assumption about the state-independence of cold-nuclear-matter effects. The wrong citation [49] and the absence of a quantitative CNM test are the load-bearing issues. The NeNe D21 anomaly also deserves more scrutiny. I recommend major revision rather than rejection, because the measurement itself is solid and a revised manuscript with a properly qualified interpretation would be publishable."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"The thing to know: this is the first measurement of all three Upsilon S-wave states in OO collisions and of Upsilon(1S,2S) in NeNe, using a pp reference at the same 5.36 TeV energy. The data are clean, the double-ratio construction is the standard one, and the systematics are handled carefully. D21 and D31 are more than five sigma below unity, and D32 sits 3.2 sigma below, which is the first hint of excited-to-ground sequential suppression in systems with <Npart> around ten. That is a genuinely new data point, and the D32 compatibility with PbPb across pT is a useful cross-check.\n\nThe soft spots are real but not fatal. The interpretation leans on the claim that initial-state nuclear effects cancel in the double ratios because they modify all Upsilon states similarly. The paper cites [49] for that, but [49] is about coherent Upsilon(1S) photoproduction, not hadroproduction, so it doesn't support the premise. The authors give no quantitative estimate for state-dependent CNM or feed-down differences, and the text itself later admits feed-down could differ between systems. Since D32 is only 3.2 sigma, a modest state-dependent CNM effect could bring it to unity. SHINCHON, which has no CNM at all, undershoots the suppression, leaving room for exactly that kind of contribution. So the data are solid, but the claim that this isolates QGP-like final-state effects is conditional, not established.\n\nThe NeNe D21 value sits 3.0 sigma below OO. The reader's take calls this \"opposite\" to the system-size hierarchy, but NeNe is the larger system, so the direction is not necessarily surprising; the magnitude is. It could be a fluctuation, but the paper should at least comment on it instead of just reporting it as a complementary check.\n\nThere are also editorial artifacts: at least one nonsensical affiliation (\"Synthetic Institute for people with CERN contract\") and several malformed DOIs in the reference list. These need to be cleaned up before publication.\n\nBottom line: this is a useful measurement for the heavy-ion and quarkonium community, and I would cite it. Send it to peer review, but the referee should push for a more careful treatment of CNM state dependence and a proper citation, and the authors should address the NeNe discrepancy and the artifacts. The measurement deserves to be published; the strong interpretation in the abstract needs softening or better support.","headline":"First Upsilon(nS) double ratios in OO and NeNe are a solid new data point; the sequential-suppression interpretation is a conditional because the CNM cancellation claim is under-supported.","tokens_in":35291,"tokens_out":4227,"would_cite":true,"duration_ms":41259,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":["25.75.Nq"],"model":"deepseek-v4-flash","headline":"The paper reports the first measurements of the three lowest Upsilon states in oxygen-oxygen collisions and the two lowest in neon-neon collisions, finding that the excited states are strongly suppressed relative to the ground state, with t","keywords":["quarkonium suppression","bottomonium","Upsilon states","oxygen-oxygen collisions","neon-neon collisions","quark-gluon plasma","sequential suppression","double ratios"],"falsifier":"A measurement of the Upsilon(nS) double ratios in proton-lead (or proton-oxygen) collisions at the same energy, where a hot medium is less likely, that shows the same deficit would falsify the final-state interpretation. More straightforwardly, if the D32 significance drops below 3 sigma with additional oxygen-oxygen data, the claimed 'first evidence' for sequential suppression would be weakened.","tokens_in":34331,"feed_emoji":"⚛️","tokens_out":5042,"duration_ms":43316,"temperature":0.7,"pith_summary":"The paper reports the first measurements of the three lowest-energy Upsilon states in oxygen-oxygen collisions, and the two lowest in neon-neon, at a nucleon-nucleon center-of-mass energy of 5.36 TeV. Using double ratios of excited-to-ground-state yields relative to proton-proton collisions, the authors find that the Upsilon(2S) and Upsilon(3S) yields are significantly suppressed, and that the Upsilon(3S) is suppressed relative to the Upsilon(2S) by more than three standard deviations. This constitutes the first evidence for sequential Upsilon suppression in light ion collisions. The pattern matches what is seen in lead-lead and gold-gold collisions, suggesting that final-state medium effects, such as a quark-gluon plasma, can emerge in very small collision systems.","feed_headline":"Excited Upsilon states suppressed in oxygen-oxygen collisions","feed_subtitle":"Ratios of Upsilon(3S) to Upsilon(2S) fall below unity, hinting that a quark-gluon plasma can form in tiny collision systems.","key_machinery":"The key observable is the double ratio D_nm = (Y(nS)/Y(mS))_AA / (Y(nS)/Y(mS))_pp, where n,m denote the Upsilon states. Constructing the ratio of the nucleus-nucleus single ratio to the proton-proton single ratio cancels experimental uncertainties and cold-nuclear-matter effects that affect all Upsilon states alike, leaving a clean probe of state-dependent, final-state suppression. The hierarchy of binding energies — 1.10, 0.54, and 0.20 GeV for the 1S, 2S, and 3S states — is what makes 'sequential' suppression observable: the more weakly bound states should dissolve earlier in a hot medium.","core_discovery":"The central claim is that in oxygen-oxygen collisions the double ratios D21 = 0.664 ± 0.055 ± 0.007, D31 = 0.392 ± 0.077 ± 0.023, and D32 = 0.59 ± 0.12 ± 0.04 are all below unity, with D21 and D31 deviating by more than five standard deviations and D32 by 3.2 standard deviations. In neon-neon collisions, D21 = 0.27 ± 0.12 ± 0.01 is even lower. The authors argue that these ratios, which cancel common uncertainties and initial-state effects, isolate final-state dissociation of the more weakly bound excited states, providing evidence for sequential suppression in systems with on average about ten participating nucleons.","pith_inferences":["If state-dependent cold-nuclear-matter effects (e.g., different nPDF modifications or feed-down for excited states) are later found to be sizable, the double-ratio interpretation would need revision; a measurement of the same states in proton-nucleus collisions at 5.36 TeV would provide a direct check.","The apparent pT-independence of D32, if confirmed with more statistics, would suggest that the suppression is dominated by the medium's early-time temperature rather than by energy-loss or formation-time effects.","One could test the 'small-system QGP' interpretation by measuring elliptic flow of the Upsilon states themselves in oxygen-oxygen collisions; a positive signal would tie the suppression to a thermalized medium."],"forward_implications":["If the claim holds, quark-gluon plasma signatures do not require large fireballs; systems with only about 10 participating nucleons can produce the same sequential pattern as lead-lead.","The compatibility of D32 between oxygen-oxygen and lead-lead collisions suggests that the dissociation of the most weakly bound state is governed by similar medium conditions, not by total volume.","The measured suppression is stronger than current hydrodynamic-plus-dissociation model predictions, indicating that the underlying dissociation mechanisms are not fully captured.","The neon-neon D21 value being lower than oxygen-oxygen provides a new handle on how suppression scales with system size among light ions.","These results provide a bridge between proton-lead and lead-lead measurements, constraining models of bottomonium production across system sizes."],"fun_headline_variants":["Oxygen-oxygen collisions show sequential Upsilon suppression","Ordered Upsilon suppression seen in light ion collisions","Tiny collision systems reveal sequential Upsilon suppression","Excited Upsilon states suppressed in order in oxygen-oxygen","Light ion collisions provide evidence for sequential Upsilon suppression"],"cache_read_input_tokens":2304,"weakest_assumption_plain":"The load-bearing assumption is that cold-nuclear-matter effects and feed-down contributions affect all three Upsilon states equally, so that any deficit in the double ratios can be attributed to final-state medium effects; if these effects are state-dependent, the observed pattern could arise without a quark-gluon plasma.","fun_headline_variants_meta":{"raw":{"variants":["Oxygen-oxygen collisions show sequential Upsilon suppression","Ordered Upsilon suppression seen in light ion collisions","Tiny collision systems reveal sequential Upsilon suppression","Excited Upsilon states suppressed in order in oxygen-oxygen","Light ion collisions provide evidence for sequential Upsilon suppression"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.001046,"raw_usage":{"total_tokens":4299,"prompt_tokens":874,"completion_tokens":3425,"prompt_tokens_details":{"cached_tokens":256},"prompt_cache_hit_tokens":256,"prompt_cache_miss_tokens":618,"completion_tokens_details":{"reasoning_tokens":3348}},"tokens_in":618,"tokens_out":3425,"duration_ms":26520,"temperature":1.0,"reasoning_tokens":3348,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-02T03:46:54.282582+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"A measurement of the Upsilon(nS) double ratios in proton-lead (or proton-oxygen) collisions at the same energy, where a hot medium is less likely, that shows the same deficit would falsify the final-state interpretation. More straightforwardly, if the D32 significance drops below 3 sigma with additional oxygen-oxygen data, the claimed 'first evidence' for sequential suppression would be weakened.","supporting_citations":[],"review_version":1}