{"id":"88f0a723-5df6-4d8d-8a9f-d7bbea098ac8","arxiv_id":"hep-ph/0406201","paper_version":3,"verdict":"CONDITIONAL","confidence":"HIGH","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":0,"one_line_summary":"A one-parameter Monte Carlo that couples BDMPS quenching weights to a Wood-Saxon collision geometry reproduces the centrality dependence of high-pt suppression and away-side correlation loss in Au-Au collisions at 200 GeV.","lead":"A Monte Carlo model (PQM) combines BDMPS parton energy-loss weights with a realistic Glauber collision geometry and one tunable parameter, then compares to RHIC high-pt data. Tuned once on central Au-Au suppression at 200 GeV, it reproduces the centrality trend, the away-side correlation loss, and gives predictions for 62.4 GeV and the LHC.","discovery_kind":"new_method","skeptic_critique":{"model":"selfhosted/deepseek-v4.1-flash","headline":"The load-bearing soft spot is the finite-energy truncation of the eikonal BDMPS weights: the two ad hoc schemes bracket a factor-2 band in R_AA and flip the sign of its pt slope, so the extracted <q-hat> ~ 14 GeV^2/fm is scheme-dependent rather than determined.","rationale":"The reader's weakest_assumption identifies exactly the right load-bearing concern: the eikonal weights applied to finite-energy partons, with the two truncation schemes bracketing a factor-2 band and flipping the pt slope. I agree this is the single most load-bearing soft spot for the central claim, and I would keep the verdict at CONDITIONAL. The paper is candid about it (Section 2 and the 'Energy-loss sampling' discussion), so this is not a new finding, but the candor does not remove the consequence: the tuned density scale is degenerate with an unphysical scheme choice, and Fig. 14 shows the shape of P(Delta E) matters where the band is narrowest. Credit where due: the parton-by-parton construction of Eqs. (8)-(16) is a genuine methodological advance over the constant-q-hat, constant-L treatments it cites, and the internal algebra is consistent (Eqs. 2, 3, 8, 16 reproduce L = 2 I_1/I_0 and q-hat = I_0^2/(2 I_1) exactly). The comparison to PHENIX and STAR data across eight centrality bins is direct evidence, and the centrality variation (factor ~4.5) exceeds the band width (factor ~2), so the model retains discriminating power even with the wide band. The secondary concerns the reader raises are real but less load-bearing for the central claim: the 62.4 GeV and 5.5 TeV predictions lean on the borrowed saturation-model scaling of Eq. (20), whose exponent is never examined at 27x the tuning energy, and the v2 result sits about 2 sigma below data at 4-6 GeV, which the authors attribute to collective flow. Both are acknowledged and both concern secondary claims rather than the 200 GeV coherent application. The absence of shipped code is a reproducibility inconvenience, not a correctness risk. My concrete test targets the untested middle ground the paper itself sketches in Section 2, which is the cleanest way to see whether the quoted band is conservative or optimistic.","tokens_in":22015,"tokens_out":5914,"duration_ms":125194,"concrete_test":"Implement the Section 2 kinematic truncation (cut omega dI/domega at the parton energy E, i.e. the <Delta E> proportional to alpha_s C_R sqrt(omega_c) sqrt(min(omega_c, E)) prescription) as a third finite-energy scheme in PQM, holding k fixed at the value tuned on central R_AA. Compare the resulting R_AA(pt) in the 0-10% and 60-80% bins to the existing band, and compute the central-to-peripheral ratio R_AA(0-10%)/R_AA(60-80%) under all three schemes. If the third scheme falls outside the quoted band, or if that ratio shifts by more than the experimental uncertainty on it, the factor-2 band understates the theoretical uncertainty and the extracted <q-hat> is not a determined quantity.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim (abstract:s2) is that a single k, tuned on central R_AA at 200 GeV, then predicts the centrality evolution of R_AA, the away-side I_AA, and v2 without retuning. That claim rests on the BDMPS quenching weights of Ref. [13], which are computed in the eikonal limit E = infinity. The paper states plainly (Section 2) that 'a full theoretical treatment of the finite parton energy case in the BDMPS framework is at present not available,' and Section 3 ('Energy-loss sampling') supplies two truncations: reweighted and non-reweighted. These differ by about a factor of two in R_AA and, by the authors' own account, in the sign of dR_AA/dp_t (slightly positive for non-reweighted, slightly negative for reweighted). Every quantitative result, including the tuned <q-hat> ~ 14 GeV^2/fm, is quoted only as a band spanning that factor of two. So the 'one free parameter' of abstract:s1 is really one parameter plus one unresolved binary modeling choice, and the headline density scale is degenerate with that choice. The concern sharpens because Fig. 14 shows the shape of P(Delta E) matters for N_part < 150: the 'only P(Delta E = 0)' variant fails there, meaning the centrality prediction is sensitive to precisely the part of the weight the eikonal approximation gets least right, and the band is narrowest in the peripheral bins where that sensitivity is largest. Notably, Section 2 itself sketches a third, arguably more physical truncation (cut omega dI/domega at E, giving <Delta E> proportional to alpha_s C_R sqrt(omega_c) sqrt(min(omega_c, E)) for E < omega_c) but never implements it, leaving the middle ground untested. This is an acknowledged limitation, not a hidden error, but the acknowledgment does not resolve it: it means the coherent-application claim is established only to within a scheme choice the theory cannot currently fix.","agreement_with_reader":"agree"},"referee_report":{"model":"selfhosted/deepseek-v4.1-flash","summary":"The manuscript presents PQM, a Monte Carlo that combines the BDMPS multiple-soft-scattering quenching weights of Salgado–Wiedemann with a Glauber/Wood-Saxon description of the Au–Au collision geometry, and applies it to high-p_t observables at RHIC. The model has one continuous scale parameter k, the normalisation of a local transport coefficient q̂(ξ) = k·T_A T_B, which is fixed on the central-collision R_AA at √s_NN = 200 GeV (giving ⟨q̂⟩ ≈ 14 GeV²/fm); the same k is then used, without retuning, for the centrality evolution of R_AA from 0–10% to 80–92%, for the away-side correlation suppression I_AA versus N_part, and for the azimuthal anisotropy v2 and its azimuthal companion observables. The authors then scale k with the saturation-model gluon density, Eq. (20), to give predictions at √s_NN = 62.4 GeV and 5.5 TeV. A substantial part of the paper is a discussion of the finite-energy truncation of the eikonal quenching weights, presented as a band between a 'reweighted' and a 'non-reweighted' scheme, and of the resulting 'black-disk' picture in which only partons produced near the surface escape.","tokens_in":22283,"tokens_out":4623,"duration_ms":89289,"significance":"The paper is a careful and, for its time, unusually complete phenomenological study: it is one of the first to fold a realistic, parton-by-parton geometry into the BDMPS weights and to confront the same one-parameter model with single-particle, di-hadron and azimuthal observables simultaneously. The post-dictions of the centrality dependence of R_AA and of I_AA, and the v2 comparison, are genuine tests rather than restatements of the fit, and the authors are explicit that the model is not applied below ~5 GeV because initial-state effects and in-medium hadronization are omitted. The falsifiable LHC prediction — R_AA ≈ 0.15, flat in p_t up to 90 GeV, in contrast to the rising Vitev–Gyulassy result — is a useful and clearly stated benchmark. The paper's main weakness is intrinsic to the input theory rather than to the authors: the eikonal weights are being used outside their domain, and the authors say so.","major_comments":[{"comment":"The headline number ⟨q̂⟩ ≈ 14 GeV²/fm is quoted as a single value, but it is the value obtained in the non-reweighted scheme; the reweighted scheme requires a different k, and the two differ by roughly a factor of two in R_AA (as the authors themselves state in §4). The abstract's 'only one free parameter' (abstract:s1) should therefore be stated precisely as one continuous parameter plus one unresolved discrete modelling choice, since the extracted density scale is degenerate with that choice. Please quote the k (and ⟨q̂⟩) obtained separately for both schemes, and state explicitly in the abstract and conclusions that the density scale carries this factor-of-two scheme ambiguity. Relatedly, §2 derives a third, arguably more physical truncation — cutting ω dI/dω at E, giving ⟨ΔE⟩ ∝ α_s C_R √q̂ √E L for E < ω_c — which is never implemented in the sampling. Either implement it as a third member of the band or justify why it is discarded, since it is the only truncation in the paper that follows from the formalism rather than being imposed on the output distribution.","section":"§3, 'Energy-loss sampling', and Fig. 3","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The paper states that the theoretical band is narrowest for semi-central and peripheral collisions because the probability of ΔE > E becomes marginal there, but Fig. 14 shows that precisely in that region (N_part < 150) the result is sensitive to the shape of the continuous part of P(ΔE): the 'only P(ΔE = 0)' variant, which keeps only the discrete weight p_0, fails for N_part < 150 while agreeing for N_part ≳ 150. The band is thus narrowest exactly where the model is most sensitive to the part of the quenching weight that the eikonal approximation constrains least. This is an internal tension in the error budget and should be stated as such: please quantify, for the 40–50% and 60–80% bins, how much R_AA moves under a plausible variation of the shape of p(ΔE) at fixed p_0, so that the reader can judge whether the peripheral agreement in Fig. 5 is meaningful or accidental.","section":"§4, Fig. 5 and Fig. 14","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The LHC prediction of R_AA ≈ 0.15, flat in p_t, and the stated disagreement with Ref. [17] rest on the density scaling of Eq. (20), n_gluons ∝ A^0.383 (√s_NN)^0.574, which gives ⟨q̂⟩ ≈ 100 GeV²/fm, a factor of seven above the RHIC value. Because the flatness of R_AA is a saturation effect, the shape may be robust, but the magnitude is not obviously so. Please show the sensitivity of the LHC R_AA to the exponent in Eq. (20) — for instance, varying the √s exponent by ±0.2 — and state whether the black-disk plateau survives. In addition, the comparison with Ref. [17] attributes the difference to the assumed gluon rapidity density; Ref. [17] also uses a different energy-loss formalism (GLV rather than BDMPS) and a different medium profile, and the manuscript should say so rather than leaving the reader with a single-cause explanation.","section":"§4, 'Extrapolation to the LHC', Fig. 10","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The single-parameter absorption toy model (all partons with L < L_max_escape escape, the rest are absorbed) is shown to reproduce both the magnitude of R_AA and the near-vanishing of I_AA in central collisions, with L_max_escape ≈ 2.5 fm. Since this is essentially the model of Ref. [14], the manuscript should state explicitly what the BDMPS weights and the parton-by-parton ω_c, R calculation add beyond that geometric picture. As written, the paper's own conclusion — that the medium acts as a black disk and that the energy-loss probability is dominated by the discrete weight p_0 — invites the reading that the full machinery is not needed for the central-collision observables. A short paragraph distinguishing what only the quenching-weight calculation can predict (e.g. the p_t dependence of R_AA, the quark/gluon differentiation, the peripheral bins where the shape of p(ΔE) matters) would substantially clarify the scope of the claim in abstract:s2.","section":"§5, 'High-energy partons from the surface', Fig. 12","authors_acknowledge":null,"authors_acknowledge_p":null}],"minor_comments":[{"comment":"The third author's name is typeset as 'G. Pai´ cc'; it should read 'G. Paic'.","section":"Title page","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The denominator dσ^h1_AA/dp_t,1 in the definition of D_AA appears to sit outside the p_t,2 and Δφ integrals, but the typesetting makes the grouping ambiguous. Please rewrite with explicit parentheses or brackets so that it is unambiguous which factors are inside the integrals.","section":"Eq. (17)","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The conclusions state that the calculated v2 lies 'about 2 standard deviations below the experimental data' at p_t ≈ 4–6 GeV, but Fig. 7 plots only statistical errors. Please specify which errors (statistical, systematic, or both) enter that 2σ statement, and note that the STAR points shown are preliminary.","section":"Fig. 7 and §6","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The caption correctly warns that, contrary to all other figures, the solid (non-reweighted) curve is the upper limit of the band here. This is easy to miss; consider adding an explicit arrow or a small inset label in the panel itself.","section":"Fig. 7 caption","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The PHENIX preliminary π⁰ comparison uses a parameterised pp reference rather than a measured one; please state this in the figure caption as well as in the text, since it affects how the agreement at p_t > 5 GeV should be read.","section":"§4, 'Nuclear modification factor at √s_NN = 62.4 GeV', Fig. 9","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The two branches of the R → ∞ gluon distribution are written with the numerical coefficients run together ('√(ω_c/2ω)' and '1/12 (ω_c/ω)²'); please check the typesetting against Ref. [13] so that the reader can verify the normalisation.","section":"§2, Eq. (4)","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The statement that the sampled impact parameter follows d⟨N_coll^AB⟩/db is clear, but the mapping from centrality class to b range is not given numerically. A short table of the b ranges and ⟨N_part⟩ used for each of the nine bins of Fig. 5 would make the centrality comparison reproducible.","section":"§3, 'Determination of ω_c and R'","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The left-hand panel uses q̂ = 1 GeV²/fm for all hadrons and q̂ = 0.75 GeV²/fm for the quark-only and gluon-only curves; the text explains why, but the caption does not. Please add one sentence to the caption so the figure is self-contained.","section":"§4, Fig. 2","authors_acknowledge":null,"authors_acknowledge_p":null}],"recommendation":"minor_revision"},"author_rebuttal":null,"desk_editor":{"model":"selfhosted/deepseek-v4.1-flash","letter":"Worth your time, with one caveat about how far the conclusions travel. The genuine advance is not the quenching weights — those are Salgado–Wiedemann — but Eqs. (8)–(16): ω_c and R computed per parton from a space-point-dependent q-hat integrated along the actual path through a Wood–Saxon Glauber overlap. That replaces the constant-q-hat, constant-L treatments it cites, and it is why the centrality scan in Fig. 5 and the I_AA comparison in Fig. 6 mean something. Those are post-dictions against data not used to fix k, and they hold up. The v2 result undershoots the 4–6 GeV data and the authors say so plainly rather than hiding it. The writing is unusually candid about its own weak points throughout, which is rare and worth noting. On the stress-test concern: it lands, but it is not a hidden error. The authors state in Section 2 that a full finite-energy treatment does not exist, and they bracket the answer with two truncations that differ by a factor of two in R_AA and flip the sign of the pt slope. So the 'one free parameter' of abstract:s1 is really one parameter plus one unresolved binary choice, and ⟨q-hat⟩ ≈ 14 GeV²/fm is degenerate with that choice. That is a fair thing to say out loud, and the paper does not quite say it that loudly. The sharper criticism is the one the stress-test half-makes: Section 2 sketches a third, more physical truncation (cut ω dI/dω at E) and never implements it, so the middle ground is untested. Fig. 14 also shows the shape of P(ΔE) matters below N_part ≈ 150, exactly where the band is narrowest — that tension is real. The bigger soft spot, though, is the energy extrapolation. The 62.4 GeV and 5.5 TeV numbers are k times the saturation-model scaling of Eq. (20), and the flat R_AA ≈ 0.15 at LHC is a strong claim resting on an exponent borrowed from a model whose validity at 5.5 TeV is never examined. The disagreement with Vitev–Gyulassy in Fig. 10 is presented as a model difference when it is partly a scaling-assumption difference. Who should read it: anyone doing jet quenching phenomenology, and anyone who will quote an LHC R_AA prediction. It deserves referees — the method is sound and the comparisons are honest — but I would want the LHC section tightened before I quoted the number.","headline":"The parton-by-parton ω_c and R construction is the real contribution here; the finite-energy band is acknowledged and honest, but the LHC 'prediction' leans harder on a borrowed scaling exponent than the paper admits.","tokens_in":23137,"tokens_out":949,"duration_ms":17649},"pith_extraction":{"msc":[],"pacs":["25.75.-q","12.38.Mh","24.85.+p"],"model":"selfhosted/deepseek-v4.1-flash","headline":"A single density scale, fixed once on central gold–gold collisions, reproduces the whole family of high-momentum suppression measurements at RHIC and predicts what the LHC should see.","keywords":["parton energy loss","jet quenching","nuclear modification factor","quark-gluon plasma","BDMPS quenching weights","Glauber collision geometry","elliptic flow","relativistic heavy-ion collisions"],"falsifier":"A measurement of the nuclear modification factor for high-$p_t$ hadrons or jets in central Pb–Pb collisions at the LHC: the model predicts a value near $0.15$ that stays flat out to $90$ GeV, so a clear rise toward $0.4$–$0.6$ at the highest transverse momenta would contradict the black-disk picture. Equally decisive would be a high-statistics measurement of $v_2$ above $7$–$8$ GeV, where the model expects only the energy-loss-induced asymmetry to remain.","tokens_in":23289,"feed_emoji":"⚛️","tokens_out":3200,"duration_ms":56979,"temperature":0.7,"pith_summary":"The paper asks whether the suppression of high-momentum particles in heavy-ion collisions — the loss of single hadrons, of away-side jet partners, and the azimuthal asymmetry of both — can all be produced by one mechanism with one adjustable number. The authors build a Monte Carlo (PQM) that takes partons from PYTHIA, lets each one traverse a realistic gold–gold overlap region built from Woods–Saxon nuclear profiles, and assigns it an energy loss drawn from the BDMPS quenching weights, computed separately for every parton from the density it actually crosses. The only free parameter is an overall scale $k$ multiplying the local transport coefficient $k$, fixed to the measured nuclear modification factor in central Au–Au at $200$ GeV; that tuning corresponds to an average $k$ of about $14$ GeV$^2$/fm. If this is right, then the centrality dependence of suppression, the vanishing of away-side correlations, and the out-of-plane/in-plane asymmetry are not three separate puzzles but three views of the same geometry-weighted energy loss. The paper then carries the same tuned parameter to $62.4$ GeV and $5.5$ TeV, and argues that at LHC energy the medium behaves as a black disk, holding $R_{AA}$ near $0.15$ flat out to the highest transverse momenta.","feed_headline":"One tuning knob reproduces jet suppression across centralities","feed_subtitle":"Fixing a single medium-density scale on central gold-gold data also yields the away-side jet loss and the azimuthal asymmetry.","key_machinery":"The load-bearing construction is the parton-by-parton conversion of a density profile into the two BDMPS parameters. For a parton born at a point in the transverse plane and moving in a sampled azimuthal direction, the local transport coefficient is taken as $k$ times the product of the two nuclear thickness functions along the path. Two path integrals, $I_0 = k$ integrated over path length and $I_1 = k$ weighted by path length, then set the characteristic radiated-gluon energy and the shape parameter: $k$ and $k$. This replaces the older practice of quoting a single constant path length and a single constant transport coefficient, and it makes the energy loss depend on where the parton was made and which way it went — which is exactly what turns collision geometry into centrality dependence and azimuthal anisotropy. The quenching weights themselves are the Salgado–Wiedemann tabulation at fixed $k$, giving the probability of radiating energy $k$, split into a discrete no-radiation weight and a continuous part.","core_discovery":"The central claim is that a Glauber-geometry description of the collision, combined with the BDMPS quenching weights applied parton by parton, needs only one number to describe the high-$p_t$ data set at $200$ GeV. Fixing the scale so that $R_{AA}$ in $0$–$10$% central Au–Au comes out right yields $k$ about $14$ GeV$^2$/fm, and the same value then reproduces the measured decrease of $R_{AA}$ from central to $80$–$92$% collisions, the away-side correlation strength $I_{AA}$ versus number of participants, and the azimuthal anisotropy $v_2$ of high-$p_t$ hadrons in non-central events. The authors emphasise that the centrality evolution is generated purely by the impact-parameter dependence of the product of the two nuclear thickness functions, with no retuning. Two consequences are drawn. First, the extracted transport coefficient is large, an order of magnitude above what a constant-path-length treatment would suggest, because many partons traverse only $2$–$3$ fm and can only be quenched if the medium is very dense. Second, the picture that emerges is a black disk: energetic partons either are absorbed or escape from a shell of roughly $2$–$3$ fm near the surface, which also explains why away-side partners of a surviving trigger particle are almost never seen.","pith_inferences":["The flat, very low $R_{AA}$ predicted for the LHC is the sharpest discriminator in the paper: a measurement of Pb–Pb $R_{AA}$ at $60$–$100$ GeV that rises with $p_t$ would rule out the black-disk reading and favour energy-loss formalisms where the eikonal approximation is softened by finite-energy or finite-density corrections.","If the medium really acts as a black disk with an escape shell of a couple of femtometres, the same geometry should imprint itself on other high-$p_t$ observables the paper does not simulate, such as the away-side correlation shape versus reaction-plane angle or the survival probability of dijets as a function of their orientation relative to the impact parameter.","The gap between the model's $v_2$ at $4$–$6$ GeV and the measured values is read here as evidence for collective flow; a natural test is whether the excess persists above $7$–$8$ GeV, where the model's energy-loss-driven asymmetry should be the only surviving contribution.","The two finite-energy truncation schemes differ by roughly a factor of two in $R_{AA}$ and even in the sign of its slope, so the extracted $k$ should be quoted as a range rather than a number until a finite-energy treatment of the quenching weights exists."],"forward_implications":["The centrality dependence of $R_{AA}$ and of the away-side correlation strength $I_{AA}$ should track the geometric overlap profile, so both observables are predicted to fall together as the number of participants grows.","In non-central collisions the model predicts $R_{AA}$ out of plane to be about $0.75$ times the in-plane value, and the away-side correlation strength about $30$% lower out of plane than in plane, both maximal around $100$–$150$ participants.","At $62.4$ GeV the same scaling of the medium density gives $k$ about $7$ GeV$^2$/fm, hence $R_{AA}$ near $0.3$ in central and near $0.7$ in semi-peripheral collisions for $p_t$ above about $5$ GeV.","At $5.5$ TeV in Pb–Pb the model gives $R_{AA}$ near $0.15$ and essentially independent of $p_t$ up to $90$ GeV, in contrast to predictions where $R_{AA}$ climbs back to $0.4$–$0.6$ at the highest momenta.","Because the relative energy loss saturates near unity for gluons and is large for quarks, the observed suppression is dominated by the probability of escaping without radiating at all, rather than by the shape of the radiated-energy distribution."],"supporting_citations":[{"why":"Supplies the BDMPS quenching weights, the tabulated energy-loss probabilities in $k$ and $k$ that the entire simulation samples from.","marker":"[13]"},{"why":"The original BDMPS energy-loss formalism whose radiated-gluon spectrum and $L^2$ scaling the paper's parameters reproduce.","marker":"[7]"},{"why":"PHENIX charged-hadron and neutral-pion $R_{AA}$ data, the measurement used to fix the single free scale parameter.","marker":"[1]"},{"why":"STAR charged-hadron $R_{AA}$ data providing the second, independent centrality scan the tuned model is checked against.","marker":"[2]"},{"why":"STAR away-side correlation measurement that the model's $I_{AA}$ versus participant number is compared with.","marker":"[3]"},{"why":"Glauber model used to convert centrality classes into impact-parameter ranges and to define the participant number.","marker":"[19]"},{"why":"Tabulated Woods–Saxon parameters supplying the nuclear density profiles that set the transverse geometry.","marker":"[20]"},{"why":"PYTHIA, used to generate the initial parton transverse-momentum spectra and the quark-to-gluon ratio at each collision energy.","marker":"[23]"},{"why":"KKP fragmentation functions used to hadronise quenched and unquenched partons on the same footing.","marker":"[25]"},{"why":"Provides the scaling of the transport coefficient with the initial gluon volume density, used to carry the tuned parameter from $200$ GeV to $62.4$ GeV and $5.5$ TeV.","marker":"[15]"}],"fun_headline_variants":["One free parameter fits R_AA, away-side loss and v2 at 200 GeV","Single tuned scale reproduces jet quenching across Au-Au centralities","PQM with one knob predicts suppression at 62.4 and 5500 GeV","Black-disk picture: partons absorbed or escape a 2-3 fm shell","One-parameter BDMPS fit yields a large transport coefficient in Au-Au"],"cache_read_input_tokens":0,"weakest_assumption_plain":"The energy-loss probabilities were computed for partons of infinite energy, but they are applied here to real partons of finite energy, and the two ways the authors patch this — forbidding losses larger than the parton energy, or letting such partons be fully absorbed — differ by about a factor of two in the resulting suppression.","fun_headline_variants_meta":{"raw":{"variants":["One free parameter fits R_AA, away-side loss and v2 at 200 GeV","Single tuned scale reproduces jet quenching across Au-Au centralities","PQM with one knob predicts suppression at 62.4 and 5500 GeV","Black-disk picture: partons absorbed or escape a 2-3 fm shell","One-parameter BDMPS fit yields a large transport coefficient in Au-Au"]},"model":"selfhosted/deepseek-v4.1-flash","effort":"low","attempts":1,"cost_usd":0.0,"raw_usage":{"total_tokens":1427,"prompt_tokens":992,"completion_tokens":435,"prompt_tokens_details":null,"completion_tokens_details":{"reasoning_tokens":341}},"tokens_in":992,"tokens_out":435,"duration_ms":7697,"image_pages":[],"temperature":1.0,"reasoning_budget":50,"reasoning_tokens":341,"transport_provider":"selfhosted","cache_read_input_tokens":0,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-11-13T08:39:36.419336+00:00","model_set":{"reader":"selfhosted/deepseek-v4.1-flash"},"pipeline_version":"pith-pipeline@v1.5.0-archive-selfhost","input_kind":null,"input_chars":null,"input_total_chars":null,"passes_missing":null,"published_standing":null,"published_confidence":null,"objection_audit":null,"run_record":null,"basis":{"kind":"not_recorded","source":null,"chars_given":null,"chars_total":null},"receipt":null,"falsifier":"A measurement of the nuclear modification factor for high-$p_t$ hadrons or jets in central Pb–Pb collisions at the LHC: the model predicts a value near $0.15$ that stays flat out to $90$ GeV, so a clear rise toward $0.4$–$0.6$ at the highest transverse momenta would contradict the black-disk picture. Equally decisive would be a high-statistics measurement of $v_2$ above $7$–$8$ GeV, where the model expects only the energy-loss-induced asymmetry to remain.","supporting_citations":[{"cited_title":"Calculating Quenching Weights","cited_arxiv_id":"hep-ph/0302184","evidence_quote":"Supplies the BDMPS quenching weights, the tabulated energy-loss probabilities in $k$ and $k$ that the entire simulation samples from."},{"cited_title":"Radiative energy loss of high energy quarks and gluons in a finite volume quark-gluon plasma","cited_arxiv_id":"hep-ph/9607355","evidence_quote":"The original BDMPS energy-loss formalism whose radiated-gluon spectrum and $L^2$ scaling the paper's parameters reproduce."},{"cited_title":"Suppressed pi^0 Production at Large Transverse Momentum in Central Au+Au Collisions at sqrt(s_NN) = 200 GeV","cited_arxiv_id":"nucl-ex/0304022","evidence_quote":"PHENIX charged-hadron and neutral-pion $R_{AA}$ data, the measurement used to fix the single free scale parameter."},{"cited_title":"Transverse momentum and collision energy dependence of high $p_{T}$ hadron suppression in Au+Au collisions at ultrarelativistic energies","cited_arxiv_id":"nucl-ex/0305015","evidence_quote":"STAR charged-hadron $R_{AA}$ data providing the second, independent centrality scan the tuned model is checked against."},{"cited_title":"Disappearance of back-to-back high $p_T$ hadron correlations in central Au+Au collisions at $\\sqrt{s_{NN}}$ = 200 GeV","cited_arxiv_id":"nucl-ex/0210033","evidence_quote":"STAR away-side correlation measurement that the model's $I_{AA}$ versus participant number is compared with."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Glauber model used to convert centrality classes into impact-parameter ranges and to define the participant number."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Tabulated Woods–Saxon parameters supplying the nuclear density profiles that set the transverse geometry."},{"cited_title":"High-Energy-Physics Event Generation with PYTHIA 6.1","cited_arxiv_id":"hep-ph/0010017","evidence_quote":"PYTHIA, used to generate the initial parton transverse-momentum spectra and the quark-to-gluon ratio at each collision energy."},{"cited_title":"Fragmentation Functions for Pions, Kaons, and Protons at Next-to-Leading Order","cited_arxiv_id":"hep-ph/0010289","evidence_quote":"KKP fragmentation functions used to hadronise quenched and unquenched partons on the same footing."},{"cited_title":"Jet Quenching","cited_arxiv_id":"hep-ph/0209038","evidence_quote":"Provides the scaling of the transport coefficient with the initial gluon volume density, used to carry the tuned parameter from $200$ GeV to $62.4$ GeV and $5.5$ TeV."}],"lane_accuracy":{"status":"not yet measured","lane":{"model":"selfhosted/deepseek-v4.1-flash","input_kind":null},"url":"https://pith.science/accuracy"},"review_version":1}