{"id":"83dd21c6-0f58-4028-a695-8dc38d35c62d","arxiv_id":"2505.00250","paper_version":1,"verdict":"UNVERDICTED","confidence":"HIGH","novelty_score":0.0,"correctness_risk":"low","formal_verification":"none","parameter_count":0,"one_line_summary":"This paper is a conference proceeding that reviews recent hard-jet correlation measurements in large and small collision systems; it contains no new experimental data, analysis, or derivation.","lead":"This conference proceeding summarizes recent experimental results on hard-jet correlations in heavy-ion and small collision systems at the LHC and RHIC. It reviews measurements from ATLAS, CMS, ALICE, STAR, and PHENIX on jet quenching, medium response, and nuclear effects.","discovery_kind":"review","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The review's signature claim—that γ-tagged versus inclusive jet S_loss is the strongest evidence for gluon vs quark quenching—rests entirely on trusting the ATLAS isospin/nPDF corrections; no independent check is presented, and a biased correction would erase the ordering.","rationale":"The paper is a review proceeding with no new data or derivation, so its central claim is necessarily a synthesis of cited experimental results. The strongest such claim—that γ-tagged versus inclusive jet S_loss is the strongest confirmation of gluon versus quark energy-loss ordering—depends on the correctness of the ATLAS extraction and its isospin/nPDF corrections. This is exactly the weakest assumption identified by the reader. My stress-test does not uncover an internal inconsistency in the review's logic; the issue is external dependence on a correction procedure that the paper does not scrutinize. Because the paper makes no original contribution to verify, and because the concern applies to the cited analysis rather than to the review's internal reasoning, the appropriate disposition remains UNVERDICTED. No change to the reader's verdict is needed.","tokens_in":9678,"tokens_out":5612,"duration_ms":64871,"concrete_test":"Using the published ATLAS unfolded yields for inclusive and photon-tagged jets, recompute the S_loss difference while replacing the default nPDF set with an independent global fit (for example, nNNPDF3.0 instead of EPPS21), propagating the full uncertainty eigenvectors; if the ordering or its significance changes, the flavor-dependent quenching claim is not robust to initial-state assumptions.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The load-bearing step is Section 2.1's assertion that the lower S_loss of photon-tagged jets compared with inclusive jets provides 'the strongest confirmation to date of larger jet quenching for gluon jets compared with quark jets.' The paper's argument is entirely inherited from the ATLAS S_loss extraction [3,4]; the review adds no independent cross-check or quantification of the systematic dependence. The comparison is interpretable as flavor-dependent final-state quenching only if the isospin and nPDF corrections applied to the two samples are unbiased. At LHC energies, γ+jet production receives different isospin and nPDF weighting than inclusive jet production, and because S_loss is derived from Pb+Pb/pp yield ratios, any residual initial-state shift is amplified. If the corrections rely on a particular nPDF set whose uncertainty eigenvectors are not propagated into the S_loss comparison, the observed ordering could reflect assumed nuclear modifications rather than the C_g versus C_q energy-loss difference. The paper does not discuss this possibility, nor does it address competing effects such as photon-isolation bias or the different kinematic coverage of the two samples. Thus the central claim is only as secure as the correction procedure in the cited analysis, and the review would need to show that the conclusion is robust across alternative nPDF treatments before the word 'strongest' is warranted.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"This paper is a conference proceedings based on the author's Hard Probes 2024 talk. It reviews recent hard-jet correlation measurements in large (Pb+Pb) and small (p+Pb, d+Au, pp) systems. The main topics are: (i) flavor dependence of jet quenching, using the ATLAS comparison of photon-tagged and inclusive jet R_AA and S_loss; (ii) color coherence effects probed by jet-substructure R_AA and CMS photon-jet substructure; (iii) path-length dependence from ATLAS dijet asymmetry as a function of jet radius and ALICE semi-inclusive hadron-jet measurements; (iv) medium response and diffusion wake in ATLAS photon-jet and CMS Z-hadron correlations; (v) searches for energy loss in small systems from CMS, STAR, and ALICE; (vi) color-fluctuation effects in p+A collisions from ATLAS and PHENIX; and (vii) nPDF constraints from ATLAS photonuclear and p+Pb dijets and CMS dijet ratios. The paper closes with an outlook on LHC Run 3, the oxygen program, and sPHENIX/STAR upgrades.","tokens_in":9884,"tokens_out":9523,"duration_ms":90676,"significance":"If accurate, the review summarizes a coherent set of recent measurements that strengthen the case for flavor-dependent parton energy loss, color decoherence, path-length dependence, and jet-induced medium response, while consistently finding no energy-loss signature in small systems. The paper is a useful, well-referenced snapshot of the field; its main strength is that it reports external measurements without introducing new derivations and it is explicit about model failures, such as the inability of current models to capture the CMS photon-jet substructure trends and the failure of JETSCAPE/LBT to describe the dijet R-dependence. Its limitations are those of a proceedings: no independent cross-checks of the cited analyses, and a few presentation errors. The central interpretive claim about the 'strongest confirmation' of quark-versus-gluon quenching is inherited from the ATLAS analysis and should be paired with a caveat about the isospin/nPDF corrections on which it rests.","major_comments":[],"minor_comments":[{"comment":"The sentence beginning 'These data provide the strongest confirmation to date of larger jet quenching for gluon jets compared with quark jets' uses a superlative that is not supported within the review, which does not compare against other flavor-sensitive measurements (e.g., b-jet or open-heavy-flavour tagged jets) and does not discuss the sensitivity of the S_loss ordering to the ATLAS isospin and nuclear-PDF corrections; suggest replacing 'strongest' with 'strong' and adding a one-sentence caveat that the conclusion inherits the assumptions of the ATLAS correction procedure.","section":"Section 2.1"},{"comment":"The sentence 'The analysis aimed to suppress centrality bias by comparing two probes similarly affected by such correctly interpreting, attributing any residual modification to final-state effects' is garbled; it should read something like 'by comparing two probes that are similarly affected by the centrality selection, so that any residual modification can be attributed to final-state effects.'","section":"Section 3.2"},{"comment":"The PHENIX ratio RdAu(pi0)/RdAu(gamma_dir) is shown in panel (b) of Figure 7, but the text refers to it twice as 'Fig. 7c' (once in the sentence about decreasing with the number of binary collisions and once in the color-fluctuation-model comparison); correct these cross-references.","section":"Section 3.2 / Fig. 7"},{"comment":"The sentence 'These findings become even more compelling when compared to ALICE's radial scan of charged-jet R_AA, where R=0.6 jets were more suppressed than R=0.2 jets' is vague because the ATLAS and ALICE radial trends point in opposite directions; suggest rewording to emphasize that the apparent tension motivates a unified interpretation, which the following sentence partly does.","section":"Section 2.2"}],"recommendation":"minor_revision","confidential_remarks":"This is a proceedings-style review rather than an original research paper. The scientific content is a faithful restatement of published results, with no load-bearing internal inconsistency. The unqualified 'strongest confirmation' in Section 2.1 is the only substantive concern, and it can be addressed with a caveat. If the journal's scope is limited to original research, the editor may wish to weigh that, but for a conference-proceedings venue the manuscript is acceptable after minor revisions."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Dear —,\n\nThis is a competent conference proceeding summarizing recent hard-jet correlation measurements from the LHC and RHIC. There is no new data or analysis, which is expected for a talk write-up. It does a real service in organizing a crowded subfield around six physics questions, covering the main results from ATLAS, CMS, ALICE, STAR, and PHENIX, and it is generally even-handed. It also notes where models fail, for instance JETSCAPE's trouble with the R-dependence of dijet asymmetry, and flags the tension between the PHENIX π0/γ ratio and other searches for energy loss. The citation pattern looks sane, and there is no circularity issue.\n\nThe soft spots are minor-to-moderate. Section 2.1 states that the ATLAS photon-tagged jet S_loss result provides \"the strongest confirmation to date of larger jet quenching for gluon jets compared with quark jets.\" That is a strong claim, and the paper's support for it is entirely inherited from the ATLAS analysis, which applies isospin and nPDF corrections. The paper mentions those corrections but does not discuss how the ordering would change under alternative nPDF treatments or if the uncertainties in those corrections were fully propagated. The stress-test note is fair: a biased correction could weaken or erase the ordering. For a review, the author need not redo the analysis, but the wording should carry a caveat, or be softened. That is the one piece of substance a referee should press on.\n\nThere are also two editing slips: the PHENIX ratio is called Fig. 7c in the text while the caption says 7b, and Section 3.2 contains the garbled phrase \"such correctly interpreting.\" Cosmetic, but they suggest a rushed final pass.\n\nOverall, this is a useful overview for a reader who wants the current state of hard-jet correlation measurements, and it deserves a serious referee—not because it breaks new ground, but because a review like this will be cited and used by people entering the field, and its interpretive language should be accurate. I'd send it out with a request to fix the \"strongest confirmation\" sentence and the caption/typo issues, then accept.\n\nBest,","headline":"A solid conference-proceeding review of hard-jet correlations, no new results, with one overstrong flavor-quenching claim and some editing slips.","tokens_in":10361,"tokens_out":3773,"would_cite":false,"duration_ms":38029,"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 review of recent hard-jet correlation measurements argues that the data now establish a flavor-dependent parton energy loss, with gluon jets quenching more than quark jets in heavy-ion collisions.","keywords":["jet quenching","quark-gluon plasma","hard-jet correlations","photon-tagged jets","fractional energy loss","dijet asymmetry","color fluctuations","nuclear PDFs"],"falsifier":"Recompute the ATLAS $S_{\\rm loss}$ comparison with alternative sets of nuclear parton distribution functions and without the isospin correction: if the gap between photon-tagged and inclusive jets shrinks to zero or reverses under a plausible alternative, the review's central claim is not robust. Alternatively, a future measurement that tags quark jets directly, for instance through $b$-quark jets or jet charge, and finds equal or smaller energy loss for gluon-enriched jets at the same $p_T$ would contradict the claimed hierarchy.","tokens_in":9416,"feed_emoji":"⚛️","tokens_out":11679,"duration_ms":105935,"temperature":0.7,"pith_summary":"This proceedings review argues that hard-jet correlation measurements have turned several long-standing questions about the quark-gluon plasma into quantitatively constrained results. The central result the author highlights is the comparison of photon-tagged jets with inclusive jets: after removing the shape of the initial parton spectrum through the fractional energy loss $S_{\\rm loss}$ and correcting for isospin and for the nuclear modification of parton distributions, gluon-initiated jets lose more energy than quark-initiated jets, as expected from their larger color charge. The same measurements constrain how energy loss depends on path length and jet radius, give a first bounded hint of the medium response opposite the jet, and find no clean evidence for energy loss in small collision systems once selection biases and color fluctuations are taken into account. A sympathetic reader would care because these correlations are the main experimental route from the macroscopic behavior of the quark-gluon plasma down to the microscopic color-charge structure of QCD.","feed_headline":"Gluon jets lose more energy than quark jets, review concludes","feed_subtitle":"Photon-tagged jets lose less energy than inclusive jets, confirming the color-charge hierarchy in the quark-gluon plasma.","key_machinery":"The load-bearing comparison is between $R_{AA}$ and the fractional energy loss $S_{\\rm loss}$ for inclusive versus photon-tagged jets. $S_{\\rm loss}$ is constructed so that the effect of the steeply falling transverse-momentum spectrum is removed, allowing the color-charge hierarchy $C_g/C_q \\sim 2.25$ to be tested directly; the photon tag selects a mostly quark-initiated sample, while inclusive jets contain a larger gluon-initiated fraction. Supporting this comparison are the dijet momentum imbalance $x_J$ and the recoil-jet yield $I_{AA}$, used as path-length and radius probes, together with the color-fluctuation model used to reinterpret event-activity biases in small collision systems.","core_discovery":"The paper's central claim is that the ensemble of hard-jet correlation measurements now supports a flavor-resolved picture of parton energy loss. In large systems, the nuclear modification factor alone is ambiguous because the $R_{AA}$ depends on the slope of the initial transverse-momentum spectrum; the review therefore puts the fractional energy loss $S_{\\rm loss}$ at the center, and on that quantity photon-tagged jets, which are mostly quark-initiated, lose less energy than inclusive jets, which carry a larger gluon fraction. The author calls this the strongest confirmation to date of the predicted color-charge hierarchy $C_g/C_q \\sim 2.25$. The same data show that narrower, more coherent jets lose less energy, that dijet momentum imbalance and recoil-jet yields across jet radii track path-length and medium-response effects, and that boson-tagged events provide a first constrained hint of a diffusion wake. In small systems, the review's claim is that apparent suppression can be traced to event-activity selection biases and color fluctuations of the projectile rather than to quark-gluon plasma formation.","pith_inferences":["An extension the paper leaves implicit: the $S_{\\rm loss}$ flavor test could be repeated with $Z$-tagged and $b$-tagged jets, where the quark fraction and the initial energy scale differ, to map the color-charge hierarchy over a wider kinematic range.","If color fluctuations explain both the event-activity bias and the neutral-pion versus direct-photon comparison, then every event-activity-selected observable in $p/d$+A collisions carries a proton-shape prior; a concrete re-analysis of published suppression data with a fluctuating-proton model should come before attributing any residual to final-state energy loss.","The tension between the dijet radius trend and the charged-jet radius trend could be resolved by a common jet definition; a same-experiment, same-observable radius scan would be a direct test of whether the difference comes from calorimeter versus track jets or from the dijet selection.","The quoted diffusion-wake amplitude of 0.5-0.8 percent is small, but it predicts a definite shape in pseudorapidity; fitting the wake width rather than assuming it would discriminate between weakly and strongly coupled medium-response models."],"forward_implications":["If the flavor hierarchy is real, inclusive jet suppression should increase with the gluon fraction, so measurements at lower $p_T$, forward rapidity, or with different jet radii should show systematically larger $S_{\\rm loss}$ than photon-tagged samples.","The radius-dependent dijet and recoil-jet results imply that larger jet radii recapture more soft medium-induced radiation, making the ratio of $R_{AA}$ between radii a direct diagnostic of the medium response and a target for the next generation of Monte Carlo generators.","The absence of a clean energy-loss signal in $p$+Pb and high-multiplicity $pp$ data, once selection biases are modeled, means future searches for the onset of quenching should use observables insensitive to event-activity selection, such as boson-tagged correlations in $p$+O and O+O collisions.","The first bounded hints of a diffusion wake imply that the medium responds collectively to the passing jet; the coming high-statistics data should sharpen the amplitude and width measurement, and a positive detection would validate models that include wake and recoil effects over those without them."],"supporting_citations":[{"why":"ATLAS measurement of photon-tagged and inclusive jet $R_{AA}$ in central Pb+Pb collisions; supplies the central quark-versus-gluon comparison.","marker":"[3]"},{"why":"Defines the fractional energy loss $S_{\\rm loss}$; the method that removes spectral-shape bias from the $R_{AA}$ comparison.","marker":"[4]"},{"why":"ATLAS dijet asymmetry across jet radii; establishes the path-length and radius dependence of jet quenching.","marker":"[11]"},{"why":"ALICE radius-dependent charged-jet $R_{AA}$; provides the contrasting radius trend that motivates a unified interpretation.","marker":"[12]"},{"why":"ALICE hadron-plus-jet recoil yield $I_{AA}$; reveals radius dependence, low-$p_T$ suppression, and high-$p_T$ enhancement attributed to medium response.","marker":"[13]"},{"why":"ATLAS search for the diffusion wake in photon-jet events; gives the hint and upper limit on the wake amplitude.","marker":"[16]"},{"why":"CMS $Z$-hadron correlation measurement; shows medium-response models describe the low-$p_T$ depletion opposite the boson.","marker":"[17]"},{"why":"CMS dijet momentum imbalance in $p$+Pb as a function of multiplicity; provides the no-quenching-in-small-systems result.","marker":"[18]"},{"why":"ATLAS measurement of $R_{CP}$ versus Bjorken-$x$; exposes the event-activity bias from the proton configuration.","marker":"[21]"},{"why":"Color-fluctuation model that explains the event-activity bias; used to reinterpret apparent suppression in small systems.","marker":"[23]"}],"fun_headline_variants":["Gluon jets lose more energy than quark jets","Photon-tagged jets confirm color-charge hierarchy","Hard-jet correlations probe flavor-dependent energy loss","Narrower jets lose less energy in quark-gluon plasma","Small-system suppression linked to selection biases"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The conclusions assume that the experimental analyses they cite are correct and unbiased; in particular, extracting the fractional energy loss for photon-tagged jets requires subtracting the different proton-neutron content of the nucleus and the nuclear modification of parton distributions, and if those subtractions are wrong the claimed ordering of gluon versus quark jet quenching would no longer follow.","fun_headline_variants_meta":{"raw":{"variants":["Gluon jets lose more energy than quark jets","Photon-tagged jets confirm color-charge hierarchy","Hard-jet correlations probe flavor-dependent energy loss","Narrower jets lose less energy in quark-gluon plasma","Small-system suppression linked to selection biases"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000248,"raw_usage":{"total_tokens":1512,"prompt_tokens":873,"completion_tokens":639,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":489,"completion_tokens_details":{"reasoning_tokens":564}},"tokens_in":489,"tokens_out":639,"duration_ms":6811,"temperature":1.0,"reasoning_tokens":564,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-16T04:46:12.947262+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Recompute the ATLAS $S_{\\rm loss}$ comparison with alternative sets of nuclear parton distribution functions and without the isospin correction: if the gap between photon-tagged and inclusive jets shrinks to zero or reverses under a plausible alternative, the review's central claim is not robust. Alternatively, a future measurement that tags quark jets directly, for instance through $b$-quark jets or jet charge, and finds equal or smaller energy loss for gluon-enriched jets at the same $p_T$ would contradict the claimed hierarchy.","supporting_citations":[{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"CMS $Z$-hadron correlation measurement; shows medium-response models describe the low-$p_T$ depletion opposite the boson."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"CMS dijet momentum imbalance in $p$+Pb as a function of multiplicity; provides the no-quenching-in-small-systems result."}],"review_version":1}