{"id":"c39946f4-9b0e-4429-8496-a664b4cb06ae","arxiv_id":"2509.08047","paper_version":1,"verdict":"CONDITIONAL","confidence":"HIGH","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":3,"one_line_summary":"In the Hybrid Model, two- and three-point energy correlators of jets in PbPb collisions cleanly separate wake and elastic-scattering contributions, with both effects needed to match CMS and ALICE data.","lead":"Physicists show that energy-energy correlators can separate the signal of quark-gluon plasma wakes from elastic scattering inside jets, and that including both best matches CMS and ALICE data. The work offers a new way to 'see' how the plasma responds to a jet passing through it.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Central claim that data require both elastic scattering and recoil wakes depends on unquantified wake normalization and lacks sensitivity scan.","rationale":"The reader's weakest_assumption is that the wake spectrum from the Cooper–Frye linearized hydrodynamic response is assumed faithful. My concern aligns with this: the central claim is the model's comparative success in matching data when both wakes and elastic scattering are included. The load-bearing issue is that this success is not shown to be robust to reasonable variations of the wake model parameters. In particular, the wake normalization and spectral shape are taken from prior self-cited works, and no sensitivity scan is provided. Without such a scan, one cannot exclude the possibility that a differently normalized wake would make the wake-only scenario fit the data equally well, or that a different elastic scattering rate would remove the need for recoil wakes. This is an addressable, numerical concern, not a theoretical inconsistency. The reader's verdict is CONDITIONAL, which is appropriate. My analysis does not change that verdict, so I recommend UNCHANGED. The concrete test—a parameter scan over wake normalization and elastic scattering strength—would directly settle whether the qualitative agreement is fragile. If the conclusion survives the scan, the central claim would be considerably strengthened; if not, the paper would need to soften its interpretation or provide a quantitative fit.","tokens_in":4054,"tokens_out":2797,"duration_ms":39922,"concrete_test":"Perform a sensitivity scan over the wake normalization and elastic scattering rate. Vary the wake energy fraction (energy deposited into the wake that emerges as soft hadrons) by factors 0.5 and 1.5, and vary the elastic scattering rate (or 2→2 cross-section normalization) by similar factors, recomputing the PbPb/pp EEC ratio for the CMS R=0.4 and ALICE R=0.2 selections in Fig. 1. Determine whether any parameter combination without both wake and elastic scattering can reproduce the data within the experimental uncertainties. If yes, the claim that data require both is not robust; if no, the claim is supported.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The paper's strongest claim—that CMS and ALICE two-point EEC data are best described only when both elastic scattering and wakes from recoiling partons are included—is supported by a qualitative comparison of model curves to data points. No error bars are shown on the model curves, and no sensitivity analysis is presented for the key model parameters, most importantly the normalization and shape of the wake contribution. The wake spectrum is generated via Cooper–Frye from a linearized hydrodynamic response, following refs. [2–4]. The fraction of the lost energy that is converted into wake hadrons, and the spectral shape of those hadrons, are model inputs that are not varied in this work. If the wake normalization were moderately increased (or its spectrum shifted harder), the 'wake-only' or 'no-recoil-wake' curves in Fig. 1 could plausibly be brought into agreement with the data, undermining the inference that both elastic scattering and recoil wakes are required. Conversely, if the elastic scattering rate were reduced, the 'both' curve might no longer be closest. Because the central conclusion rests on the model's ability to reproduce the data and on the separation of wake and elastic effects, the lack of a parameter sensitivity study is a load-bearing gap. This is not a claim that the model is wrong; it is a claim that the evidence presented does not yet uniquely determine that both ingredients are necessary.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The manuscript presents Hybrid Model calculations of two- and three-point energy-energy correlators (EECs) in Pb+Pb collisions and compares them to recent CMS and ALICE measurements. The central claim is that the PbPb/pp EEC ratio is best described when the model includes both elastic (Molière) scattering of jet partons off quasi-particles and hydrodynamic wakes generated by the energy lost by all partons, including the elastically scattered recoil partons. The paper further proposes a new EEC measurement extending to angular scales beyond the jet radius and presents three-point EEEC shape projections as a two-stage microscope for separating wake and elastic-scattering contributions.","tokens_in":4428,"tokens_out":5977,"duration_ms":68528,"significance":"If the central claim is correct, the comparison would be an important external benchmark: the EEC data would already discriminate among mechanisms of jet–medium interaction, supporting the presence of quasi-particle-like scatterings alongside strongly-coupled wake response. The paper is strongest in its concrete falsifiable predictions: the R_L>R region in Fig. 2 is a clean, model-driven target for experiment, and the EEEC shape projections in Fig. 3 make qualitative distinctions between wake and elastic effects. The comparison in Figs. 1–3 is not a fit to the same data — the model parameters were fixed in earlier R_AA-style studies — so the agreement is a genuine prediction rather than a circular fit. However, the manuscript's main evidence is qualitative; the absence of model uncertainties and parameter sensitivity prevents the reader from assessing how strongly the data actually discriminate between the variants.","major_comments":[{"comment":"The statement that the 'both' curve 'tracks the observed rise ... most closely' is supported only by visual inspection. No goodness-of-fit statistic, no chi-square per point, and no statistical uncertainty band on the model curves is given. Since the central conclusion is a comparative ranking of four model variants, please provide a quantitative measure of agreement over the plotted R_L range and show Monte Carlo or bootstrap uncertainties on the model curves.","section":"Sec. 2, Fig. 1"},{"comment":"The wake contribution is generated by Cooper–Frye from a linearized hydrodynamic response following Refs. [2–4]. Its normalization and spectral shape are model inputs that are not varied. If the wake normalization were moderately increased, the 'wake-only' curve in Fig. 1 could plausibly match the data; if the elastic scattering rate were reduced, the 'both' curve might no longer be closest. A sensitivity scan over the wake normalization/freeze-out temperature and the elastic scattering rate is needed to support the claim that both ingredients are required by the data.","section":"Sec. 1, Sec. 2"},{"comment":"The abstract and Sec. 2 state that data are best described 'when the elastically scattered recoil-partons produce their own wakes,' but the four curves shown do not isolate wakes of recoil partons from wakes of the deflected parent partons or from the elastic deflection of the hard shower. The difference between 'elastic + wake' and 'wake-only' includes both the elastic shower modification and all additional wakes. To make the recoil-wake attribution rigorous, show a variant with elastic scatterings enabled but only original-parton wakes included, or otherwise quantify the separate contribution of recoil-parton wakes.","section":"Sec. 2, Fig. 1"}],"minor_comments":[{"comment":"Duplicate 'the' in the Ramón y Cajal funding sentence.","section":"Acknowledgements"},{"comment":"Reference [7] is an ALICE conference talk; if a journal version exists or becomes available, it should be cited instead of the talk.","section":"Ref. [7]"},{"comment":"The text says the shape-dependent EEEC is a function of three angles, but Figs. 3 and the preceding paragraph present projections onto x and y separately. Please clarify that the full correlator is a function of (R_L, x, y) and that projections are shown.","section":"Sec. 3"},{"comment":"The track-pT cut 'p_ch^T > 1 GeV' and jet pT ranges should be typeset consistently with the text, and it would be helpful to define R_L in the caption for readers unfamiliar with the EEC variable.","section":"Fig. 1 caption"}],"recommendation":"major_revision","confidential_remarks":"The paper is likely a proceedings contribution, and its brevity is understandable. Nevertheless, the central claim is comparative and quantitative in nature; without model uncertainties or a parameter scan it cannot be fully evaluated. I would encourage the editor to request a modest but substantive revision that adds a quantitative comparison and a sensitivity statement, rather than merely softening the language."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Colleague,\n\nYou should know this paper before the next heavy-ion journal club: it's the first EEC-based study I've seen that claims both elastic scattering and wakes from recoiling partons are already visible in CMS and ALICE PbPb/pp EEC data. That claim is plausible but not yet nailed down, because the evidence is visual—model curves against data points, no error bands, no fit statistic, no parameter scan.\n\nWhat's new: the authors add elastic scattering with recoil-parton wakes to their earlier Hybrid Model EEC predictions, compare to the latest CMS and ALICE measurements, and propose a new measurement—extending R_L beyond the jet radius—that they argue is a direct wake signal. The three-point EEEC shape projections are a nice addition, separating angular scale from triangle shape. The paper is honest about its model dependence, citing its own earlier work for the wake implementation. That's not circular: the EEC comparison is an external benchmark, not a fit to the same data.\n\nThe soft spot is real. The central claim that the 'both' curves track the data most closely is supported only by eye. The wake spectrum is generated via Cooper–Frye from a linearized response, and its normalization and shape come from prior papers (refs [2–4]). If the wake normalization were moderately larger, the wake-only curve could plausibly match the data; if the elastic rate were smaller, the 'both' curve might not be closest. The paper doesn't provide the sensitivity study that would settle this. That's a load-bearing gap for the two-point claim, but it's addressable in revision.\n\nThe R_L > R proposal is genuinely useful and untested; the three-point predictions are forward-looking and could be sharpened once data exist. The lack of error bars on model curves is a minor issue by comparison.\n\nFor a heavy-ion phenomenologist or jet substructure person, this is worth a serious read. The paper deserves peer review, not a desk reject—the gaps are fixable, and the new measurement proposal justifies referee time.\n\nSend it to review and ask for a sensitivity scan and a quantitative comparison metric.","headline":"Plausible and timely, but the two-ingredient claim rests on visual curve comparison, not a sensitivity study; the R_L > R proposal is the real gem.","tokens_in":4875,"tokens_out":2195,"would_cite":true,"duration_ms":26496,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":["25.75.-q","12.38.Mh"],"model":"deepseek-v4-flash","headline":"Two-point jet correlator data already require both hydrodynamic wakes and quasi-particle scattering, and a new angular window can image the wake alone.","keywords":["energy-energy correlators","jet quenching","quark-gluon plasma","Hybrid Model","elastic scattering","hydrodynamic wake","jet substructure","heavy-ion collisions"],"falsifier":"Carry out the paper's proposed measurement: the PbPb/pp EEC ratio for 80 < pT < 100 GeV, R=0.2 charged-jets with a 150 MeV track-pT threshold, extended to angular separations up to 2R. If the ratio does not rise steeply above unity for R_L ≳ R — the region that only soft, peripheral hadrons can populate — the wake-dominated picture is falsified. A second check: measure the ratio at several track-pT thresholds; if the large-R_L enhancement does not grow as the threshold is lowered, the soft-hadron wake component is not the source of the rise.","tokens_in":3993,"feed_emoji":"🌊","tokens_out":11420,"duration_ms":115663,"temperature":0.7,"pith_summary":"This paper argues that the angular pattern of energy inside jets in heavy-ion collisions can tell apart two different faces of the quark-gluon plasma (QGP): a strongly coupled liquid that responds like a fluid when a jet dumps energy into it, and a gas of quark- and gluon-like quasi-particles that can knock jet constituents sideways. Using the Hybrid Model — a perturbative parton shower combined with holographic energy loss, Cooper-Frye hydrodynamic wakes, and 2-to-2 elastic scatterings — the authors compute two- and three-point energy-energy correlators (EECs) and compare the PbPb/pp ratio with CMS and ALICE data. Their central claim: the calculation that includes both the wakes and the elastic scatterings tracks the measured rise of the ratio toward larger angular separations most closely; turning off either ingredient degrades the fit. If this is right, the existing data already demand both liquid-like wake excitation and quasi-particle elastic scattering in the same plasma, with the wakes of the recoiling scattered partons — not just the original jet's wake — shaping the observable. The paper also proposes a new measurement, pushing EECs to angular separations beyond the jet radius, which should isolate the wake signal alone.","feed_headline":"Wakes plus quasi-particle kicks best match jet-correlator data","feed_subtitle":"If right, CMS and ALICE data already require both liquid wakes and quasi-particle kicks in the QGP.","key_machinery":"The carrying objects are the two-point and three-point energy-energy correlators (EEC/EEEC): the angular distribution of energy-weighted pairs, and of particle triplets, inside a jet, expressed as a PbPb/pp ratio to cancel the vacuum shower baseline. The physics input is the Hybrid Model — a perturbative DGLAP/PYTHIA8 parton shower; a holographic energy-loss formula that deposits the lost momentum into the plasma; the Cooper-Frye prescription applied to the linearized hydrodynamic stress-energy perturbation to generate the soft hadron wake spectrum; and 2-to-2 elastic (Molière) scatterings that deflect a jet parton and kick a medium quasi-particle into recoil, after which both partons lose e","core_discovery":"The paper's central claim is that the CMS and ALICE two-point EEC data already discriminate between the competing ways a jet interacts with the quark-gluon plasma. The closest match comes from Hybrid Model calculations in which jet partons both lose energy to the medium — exciting hydrodynamic wakes — and scatter elastically off quasi-particles, with the deflected jet parton and the recoiling medium parton each subsequently exciting its own broad wake. This combination reproduces the observed rise of the PbPb/pp ratio toward large angular separation R_L, while removing either ingredient under-shoots the data. The three-point correlator then acts as a two-stage microscope: the overall scale R","pith_inferences":["The argument implies a monotonic, testable trend: as the track-pT threshold is lowered from 1 GeV toward 150 MeV, the large-R_L enhancement of the PbPb/pp ratio should grow if soft wake hadrons are really its source; measuring the ratio at several thresholds would cross-check the wake hypothesis without relying on the model's details.","If quasi-particle scattering is genuinely required by the data, the same elastic kicks should leave imprints in other angularly sensitive jet observables — for instance, the distribution of the energy of the highest-pT sub-leading constituents, or large-angle jet-hadron correlations — offering independent confirmation outside EECs.","The shape decomposition could be pushed further than the paper does: the width and orientation of the equilateral enhancement at large R_L may be sensitive to the anisotropy of the wake (e.g., its response to collective flow), potentially making the EEEC a quantitative probe of the medium's transport properties.","The dominance of recoiling-parton wakes at R_L > 0.2 suggests that jets undergoing more hard scatterings should show larger medium-response signals; reselecting the jet sample by the number or momentum of its wide-angle constituents could test this correlation."],"forward_implications":["The measured rise of the PbPb/pp EEC ratio toward large R_L implies that the wakes of elastically scattered, recoiling partons — not only the wake of the original jet partons — carry the jet's deposited energy, and that this 'deflection memory' is visible in existing CMS and ALICE data.","The angular window 0.1 ≲ R_L ≲ 0.2 in the R=0.2 charged-jet EEC is where elastic scattering's deflection of hard, collinear constituents shows up, so data in that window constrain the presence of quasi-particle scatterings in the QGP.","Extending EEC measurements to R_L > R (beyond the jet radius) with a 150 MeV track-pT threshold — kinematically inaccessible to pairs with a hard core constituent — should reveal a marked PbPb/pp enhancement that isolates the wake of the jet.","In the three-point EEEC, an enhancement of equilateral triangles at large R_L diagnoses the angular structure of the wake, while a broad, uniform uplift at small R_L diagnoses elastic scattering — giving scale and shape information about jet-medium interactions.","Lowering the track-pT threshold generally increases the wake's leverage on the EEC, which is why the proposed low-threshold, extended-R_L variant is the sharpest test of the wake picture."],"supporting_citations":[{"why":"Supplies the holographic energy-loss formula used to determine how much momentum each jet parton deposits into the plasma.","marker":"[1]"},{"why":"Prior study that supplies the EEC framework and the triangle parametrization of three-point correlators on which this paper builds.","marker":"[2]"},{"why":"Details the shape and normalization assumptions of the wake spectrum adopted in the Hybrid Model here.","marker":"[3]"},{"why":"The Cooper-Frye implementation that converts the linearized hydrodynamic stress-energy response into the soft hadron wake.","marker":"[4]"},{"why":"Implements 2-to-2 elastic scatterings and the wakes of the deflected and recoiling partons, the key new ingredient distinguishing the best-fit curves.","marker":"[5]"},{"why":"The CMS R=0.4 inclusive-jet EEC measurement the model is compared against (left panel of Fig. 1).","marker":"[6]"},{"why":"The ALICE R=0.2 charged-jet EEC measurement the model is compared against (right panel of Fig. 1).","marker":"[7]"}],"fun_headline_variants":["Wakes plus recoil kicks best explain jet correlator data","QGP jets need both liquid wakes and particle kicks","Energy correlators reveal dual nature of jet-medium response","CMS and ALICE data favor wakes plus hard-scatter kicks","Hybrid model: jets excite wakes and recoil kicks to match data"],"cache_read_input_tokens":2688,"weakest_assumption_plain":"The load-bearing assumption is that the wake spectrum — the soft hadrons produced from the momentum a jet deposits in the plasma, computed with the Cooper-Frye prescription from a linearized hydrodynamic response — faithfully represents what the real medium emits; if the true wake were materially weaker, narrower, or differently normalized, the large-R_L enhancement attributed to wakes would shrink or shift and the data comparison would no longer single out the wake-plus-scat","fun_headline_variants_meta":{"raw":{"variants":["Wakes plus recoil kicks best explain jet correlator data","QGP jets need both liquid wakes and particle kicks","Energy correlators reveal dual nature of jet-medium response","CMS and ALICE data favor wakes plus hard-scatter kicks","Hybrid model: jets excite wakes and recoil kicks to match data"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000899,"raw_usage":{"total_tokens":3723,"prompt_tokens":776,"completion_tokens":2947,"prompt_tokens_details":{"cached_tokens":256},"prompt_cache_hit_tokens":256,"prompt_cache_miss_tokens":520,"completion_tokens_details":{"reasoning_tokens":2863}},"tokens_in":520,"tokens_out":2947,"duration_ms":20796,"temperature":1.0,"reasoning_tokens":2863,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-04T21:21:47.619448+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Carry out the paper's proposed measurement: the PbPb/pp EEC ratio for 80 < pT < 100 GeV, R=0.2 charged-jets with a 150 MeV track-pT threshold, extended to angular separations up to 2R. If the ratio does not rise steeply above unity for R_L ≳ R — the region that only soft, peripheral hadrons can populate — the wake-dominated picture is falsified. A second check: measure the ratio at several track-pT thresholds; if the large-R_L enhancement does not grow as the threshold is lowered, the soft-hadron wake component is not the source of the rise.","supporting_citations":[{"cited_title":"Sensitivity of jet observables to the presence of quasi-particles in QGP","cited_arxiv_id":"2208.13593","evidence_quote":"Implements 2-to-2 elastic scatterings and the wakes of the deflected and recoiling partons, the key new ingredient distinguishing the best-fit curves."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"The ALICE R=0.2 charged-jet EEC measurement the model is compared against (right panel of Fig. 1)."}],"review_version":1}