{"id":"ec165a45-9dd6-4379-820c-165d2697dd3b","arxiv_id":"2412.05178","paper_version":3,"verdict":"CONDITIONAL","confidence":"HIGH","novelty_score":4.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":2,"one_line_summary":"EPOS4 with a hadronic afterburner reproduces resonance suppression patterns, and the extracted hadronic phase lifetime increases with multiplicity and system size, remaining non-zero in high-multiplicity pp collisions.","lead":"This paper uses the EPOS4 simulation, with late-stage particle interactions switched on or off, to study how short-lived resonances behave in proton-proton and lead-lead collisions at the LHC. It estimates the duration of the hadronic phase between freeze-out stages and finds it grows with system size and is non-zero even in high-multiplicity proton-proton collisions.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The chemical baseline for Eq. 1 is taken from minimum-bias pp simulated with UrQMD ON, even though the method assumes no hadronic phase there; the reported tau values may be differential (tau_high - tau_minbias), not absolute hadronic-phase durations.","rationale":"The reader's weakest_assumption correctly identifies the most load-bearing concern. The central claim is a quantitative estimate of hadronic phase lifetime, and the absolute values rest on the chemical baseline. Since the paper's own model includes UrQMD in all pp events, the assumption of no hadronic phase in pp is contradicted by the very calculation used to form the baseline. This does not overturn the qualitative multiplicity trend, which survives as a difference between high-mult and min-bias, but it undermines the absolute '0.5-1 fm/c' interpretation. The paper is otherwise a solid EPOS4 study: it reproduces ALICE resonance suppression trends, uses a large sample, and transparently lists assumptions. Credit is due for the UrQMD ON/OFF comparison throughout, which makes the proposed test straightforward. Because the concern is testable and the qualitative conclusions are likely robust, the appropriate verdict remains CONDITIONAL, pending the sensitivity check. No ad hominem; this is an argument-level issue.","tokens_in":19578,"tokens_out":5493,"duration_ms":54986,"concrete_test":"Recompute the tau values in Fig. 11 for EPOS4 using the UrQMD-OFF yield ratio as [h*/h]_chemical, for rho0/pi, K*0/K, and Lambda*/Lambda in the same multiplicity classes, and compare with the published min-bias-pp-baseline values. If the high-multiplicity pp tau moves from 0.5-1 fm/c by more than ~20%, or if the non-zero signal becomes consistent with zero within statistical uncertainties, the absolute hadronic-phase duration claim is baseline-dependent and should be stated as differential. A simpler proxy: compare EPOS4-with-UrQMD minimum-bias pp ratios to EPOS4-without-UrQMD ratios; if they differ by more than the statistical uncertainty, the no-hadronic-phase-in-pp assumption is violated within the model itself.","verdict_should_be":"UNCHANGED","load_bearing_attack":"Section 3.5 assumes 'no hadronic phase forms in pp collisions due to the small system size' and therefore uses the yield ratio in minimum-bias pp as [h*/h]_chemical in Eq. 1 ([h*/h]_kinetic = [h*/h]_chemical exp(-tau/tau_h*)). But the EPOS4-with-UrQMD simulations that supply these ratios include the hadronic afterburner in every pp multiplicity class, so the minimum-bias pp ratio already contains rescattering suppression. Under the exponential-decay model, the extracted tau is then tau_high-mult - tau_min-bias rather than tau_high-mult. This shifts every absolute value in Fig. 11 downward and makes the headline 'non-zero time duration (~0.5-1 fm/c) in high-multiplicity pp' an excess over an unquantified hadronic phase in minimum-bias pp, rather than an absolute hadronic phase duration. The paper flags the assumption but provides no sensitivity test, despite having the UrQMD-OFF calculation in the same model that would give the true chemical reference. This is the most load-bearing weakness because it directly controls the numerical headline claim; the other stated assumptions (negligible regeneration, simultaneous freeze-out) are acknowledged and only affect the 'lower limit' interpretation.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The manuscript presents an EPOS4 study of hadronic resonance production in pp collisions at sqrt(s)=13.6 TeV and Pb-Pb collisions at sqrt(s_NN)=5.36 TeV, comparing simulations with the UrQMD hadronic afterburner enabled and disabled. It reports pT spectra, resonance-to-stable yield ratios, baryon-to-meson ratios, mean pT versus reduced mass, and strangeness enhancement, and it uses the exponential-decay formula (Eq. 1) to estimate a lower limit for the hadronic phase duration tau from the suppression of rho, K*0, and Lambda* relative to stable hadrons. The main claims are that EPOS4+UrQMD reproduces the qualitative system-size dependence of resonance suppression seen by ALICE, and that tau increases with multiplicity, remaining non-zero at about 0.5-1 fm/c in high-multiplicity pp collisions.","tokens_in":19831,"tokens_out":5458,"duration_ms":49265,"significance":"If the central claims hold, the paper offers a useful model-based diagnostic of the hadronic phase and demonstrates the value of the EPOS4 UrQMD ON/OFF comparison. The strengths are the systematic confrontation with ALICE data, the internal consistency of the suppression ordering with resonance lifetimes, and the absence of parameter fitting in the tau extraction. The main risk is the chemical baseline assumption in Section 3.5, which directly controls the numerical headline claim; because the baseline is taken from minimum-bias pp with UrQMD ON, the extracted tau may be an excess over hadronic rescattering already present in the baseline rather than an absolute hadronic phase duration. The paper flags this assumption but does not test its sensitivity, even though the UrQMD-OFF calculation in the same model provides a ready chemical reference.","major_comments":[{"comment":"The chemical reference [h*/h]_chemical is taken from minimum-bias pp collisions simulated with UrQMD ON, despite the stated assumption that no hadronic phase forms in pp. Since the UrQMD ON simulation includes hadronic rescattering, the minimum-bias pp ratio already contains suppression relative to the true chemical value. Under the exponential-decay model, the tau extracted for high-multiplicity pp is therefore tau_high-mult - tau_min-bias, not an absolute hadronic phase duration; this directly affects the headline claim of a non-zero ~0.5-1 fm/c duration in high-multiplicity pp collisions. The authors have the UrQMD-OFF calculation available, which would provide an actual chemical reference, and I request a sensitivity test using that baseline, or a clear report of both interpretations, before the numerical claim is accepted. The current text flags the assumption but provides no quantitative assessment of its impact.","section":"3.5, Eq. (1)"},{"comment":"Assumption (i) of Eq. (1) states that regeneration effects are negligible, but Sections 3.1 and 3.4 attribute the comparable net suppression of Sigma* and Lambda* to substantial regeneration for Sigma*, and state that regeneration contributions follow the order R_{K+p} < R_{K+pi} < R_{Lambda+pi}. The tau extraction uses rho, K*0, and Lambda*, so the assumption may be acceptable, but the paper should justify that this hierarchy makes regeneration negligible for exactly those resonances, or quantify the systematic bias introduced by regeneration. As written, the same paper both relies on and disputes the negligible-regeneration assumption without reconciliation, which weakens the interpretation of tau as a lower limit.","section":"3.5 vs 3.1/3.4"},{"comment":"Fig. 11 shows that the extracted tau differs substantially among rho, K*0, and Lambda*, with longer-lived resonances giving larger timescales. If tau were a common hadronic-phase property, all resonances would give the same value within regeneration effects; the spread suggests that the exponential-decay model is incomplete. The paper acknowledges this but does not assess how the central trend of 'tau increases with system size and is non-zero in high-multiplicity pp' depends on the choice of resonance. I recommend adding a systematic variation or stating explicitly that the claim is per-resonance and not a single common phase duration.","section":"3.5, Fig. 11"}],"minor_comments":[{"comment":"The word 'multiplicity' is misspelled as 'multiplicty' in the caption.","section":"Fig. 2 caption"},{"comment":"'handel' should be 'handle' in 'It is important to properly handel feed-down contribution'.","section":"3.3"},{"comment":"The sentence 'The EPOS4 model with MCE framework, which reproduces the observed behavior seen in the experimental measurements.' is a fragment; it should be rephrased as a complete sentence.","section":"3.6"},{"comment":"There is a formatting glitch in 'T able 1' at the start of the table caption.","section":"Section 2, Table 1"},{"comment":"In 'lifetimes of a few fm/care', a space is missing between 'fm/c' and 'are'.","section":"Abstract"},{"comment":"The central quantitative result would be easier to assess if the extracted tau values and their statistical uncertainties were collected in a table for each resonance and multiplicity class, rather than only shown in Fig. 11.","section":"3.5"}],"recommendation":"major_revision","confidential_remarks":"The paper is appropriate in scope for the journal, and the central issue identified in the report is specific and testable. The authors have in hand the UrQMD-OFF calculation needed to remove the baseline ambiguity, so major revision rather than rejection seems the right outcome. The other two major points can be addressed by a clearer justification of the negligible-regeneration assumption and a more cautious interpretation of the per-resonance tau values."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"The paper is a solid EPOS4 model study of resonance production at Run 3 energies. The genuinely new bit is applying EPOS4 with the UrQMD afterburner to high-multiplicity pp at 13.6 TeV and Pb–Pb at 5.36 TeV, with careful reconstructible/non-reconstructible resonance accounting and 1.5–5M events per setting. The UrQMD ON/OFF comparison is a clean diagnostic, and the pattern it yields—suppression ordered by resonance lifetime, with regeneration partially offsetting rescattering for Sigma* and Lambda*—is internally consistent and matches ALICE data qualitatively. The model bookkeeping is honest, showing data/model deviations where they exist, like the p/phi overshoot at pT > 1.5 GeV/c, rather than hiding them.\n\nThe main soft spot is the hadronic-phase lifetime extraction in Section 3.5. Eq. 1 uses an exponential decay law, which is standard, but the chemical reference is taken from minimum-bias pp simulated with UrQMD ON. If the minimum-bias pp hadronic phase is non-zero—and the model itself suggests it is, since high-mult pp already shows UrQMD ON/OFF differences—then the extracted tau is actually tau_high − tau_MB, not an absolute hadronic phase duration. The authors explicitly state the assumption (no hadronic phase in pp) but do not test it, even though the UrQMD-OFF run would give the true chemical baseline. This does not break the paper: the increasing trend with multiplicity and the non-zero high-mult pp excess survive regardless, and if anything the true absolute durations are larger than reported. But the numerical headline values in Fig. 11 and the abstract should be read as differential, and the authors should show the sensitivity. This is a moderate, fixable weakness, not a disqualifying one.\n\nNovelty is limited—the qualitative suppression patterns and non-zero pp hadronic phase were already in the cited ALICE papers and prior EPOS3 studies—but this is a legitimate extension to Run 3 energies and a useful benchmark for future LHC data. It is not trying to resolve a long-open problem, and it ships a reproducible model calculation with no fitted parameters.\n\nRecommendation: this deserves a serious referee. The paper is cleanly written, the model work is careful, and the one load-bearing assumption needs an explicit sensitivity test, which the authors have the tools to do. I would accept it for review with a request to address the baseline issue and soften the absolute-tau language.","headline":"Solid EPOS4 benchmark for Run 3 resonance data, but the headline hadronic-phase lifetimes are differential (high-mult minus min-bias), not absolute, because the chemical baseline already includes UrQMD rescattering.","tokens_in":20410,"tokens_out":3821,"would_cite":true,"duration_ms":37321,"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":"Resonance-to-stable yield ratios imply a non-zero hadronic-phase lifetime that grows from high-multiplicity pp to central Pb–Pb collisions at LHC energies.","keywords":["hadronic resonances","hadronic phase lifetime","EPOS4","UrQMD","rescattering","regeneration","strangeness enhancement","small collision systems"],"falsifier":"Run the same high-multiplicity pp events through EPOS4 with UrQMD turned off: if $K^{*0}/K$ no longer falls below the minimum-bias pp baseline, the non-zero $\\tau$ is a genuine afterburner effect, whereas if the suppression remains, the signal is produced before the hadronic phase and the exponential-decay interpretation would be wrong.","tokens_in":19364,"feed_emoji":"⏱️","tokens_out":9608,"duration_ms":95692,"temperature":0.7,"pith_summary":"This paper uses the EPOS4 model with the UrQMD hadronic afterburner switched on and off to show that the suppression of short-lived hadronic resonances in pp and Pb–Pb collisions is a real final-state effect. The central claim is that yield ratios such as $K^{*0}/K$, $\\rho^0/\\pi$, and $\\Lambda^{*}/\\Lambda$ can be converted, through the exponential decay law, into a lower limit on the duration of the hadronic phase, and that this duration increases with charged-particle multiplicity and system size, reaching about 0.5–1 fm/c even in high-multiplicity pp collisions. If true, resonance ratios become a practical clock for the hadronic phase in both heavy-ion and small collision systems, and EPOS4 with UrQMD becomes a quantitative tool for interpreting such measurements. The paper also connects the same machinery to strangeness enhancement, radial flow, and baryon-to-meson ratios.","feed_headline":"Hadronic phase lasts at least 0.5–1 fm/c in high-multiplicity pp","feed_subtitle":"EPOS4 models with the UrQMD afterburner show the time grows with multiplicity and system size from pp to Pb–Pb.","key_machinery":"The central object is the yield ratio of a short-lived resonance to a stable hadron of similar quark content, read through the exponential decay law $[h^*/h]_{\\mathrm{kinetic}} = [h^*/h]_{\\mathrm{chemical}} \\, e^{-\\tau/\\tau_{h^*}}$. Choosing ratios such as $K^{*0}/K$ cancels strangeness-related production effects and isolates rescattering in the hadronic phase, converting a measured suppression into a time. The simulations use EPOS4 with a core–corona separation and microcanonical hadronization, plus UrQMD as a hadronic afterburner; toggling UrQMD on and off is what isolates the hadronic-phase signal.","core_discovery":"The paper reports that switching UrQMD on makes short-lived resonance spectra and yields fall relative to stable hadrons at low $p_{\\mathrm{T}}$, with suppression ordered roughly by vacuum lifetime ($\\rho^0 < \\Delta^{++} < K^{*0} < \\Sigma^{*\\pm} \\sim \\Lambda^{*} < \\Xi^{*0} < \\phi$), while the long-lived $\\phi$ stays nearly unchanged. It then estimates the hadronic-phase duration $\\tau$ from integrated resonance-to-stable ratios using $[h^*/h]_{\\mathrm{kinetic}} = [h^*/h]_{\\mathrm{chemical}} \\, e^{-\\tau/\\tau_{h^*}}$, taking the result as a lower limit because regeneration is neglected. The extracted $\\tau$ increases with charged-particle multiplicity and system size, and it is non-zero, about 0.5–1 fm/c, in high-multiplicity pp collisions. Different resonances give different values of $\\tau$, which the paper attributes to regeneration and decay-daughter cross-sections beyond the simple exponential model.","pith_inferences":["Because the minimum-bias pp ratio is assumed to be the no-hadronic-phase reference, the absolute value of $\\tau$ is only as reliable as that assumption; the increasing trend with multiplicity would survive, but the 0.5–1 fm/c number is a differential estimate.","A natural extension is to apply the same $\\tau$ extraction to p–Pb collisions at matched multiplicity; if the paper's picture is right, the resonance ratios should fall on the same curve as pp and Pb–Pb, directly testing multiplicity scaling.","The spread among $\\rho^0$, $K^{*0}$, and $\\Lambda^{*}$ suggests that fitting all three simultaneously with an equation that includes regeneration would yield both a more physical $\\tau$ and a handle on resonance–medium cross-sections."],"forward_implications":["A non-zero hadronic-phase duration in high-multiplicity pp collisions would mean small collision systems do have a measurable late hadronic stage, not only a hydrodynamical core.","The increasing lower-limit $\\tau$ with charged-particle multiplicity provides a single curve connecting small and large collision systems, making resonance ratios a system-size clock.","The species-dependent $\\tau$ values found for $\\rho^0$, $K^{*0}$, and $\\Lambda^{*}$ imply that regeneration and decay-daughter cross-sections must be modeled explicitly rather than absorbed into a single freeze-out temperature.","EPOS4 with UrQMD reproduces the measured suppression order and the $K^{*0}/K$ multiplicity trend, so the same setup can give quantitative predictions for unmeasured resonances such as $\\Delta^{++}$ and heavier baryonic states."],"supporting_citations":[{"why":"Supplies the Pb–Pb $K^{*0}/K$ data and the ratio-to-lifetime method used to extract $\\tau$.","marker":"[7]"},{"why":"Provides high-multiplicity pp and p–Pb $K^{*0}/K$ suppression data that motivate a non-zero hadronic phase in small systems.","marker":"[13]"},{"why":"Confirms the decreasing $K^{*0}/K$ trend in high-multiplicity small systems, strengthening the non-zero $\\tau$ conclusion.","marker":"[14]"},{"why":"Supplies pp $K^{*0}/K$ measurements at 13 TeV used as the small-system baseline and comparison.","marker":"[3]"},{"why":"Provides multiplicity-dependent $\\rho^0/\\pi$ and related resonance ratios used for the $\\tau$ estimate.","marker":"[5]"},{"why":"Supplies $\\Lambda^{*}/\\Lambda$ data that drive the baryonic-resonance suppression analysis and its $\\tau$ estimate.","marker":"[12]"},{"why":"Defines the EPOS4 core–corona and microcanonical hadronization framework used for all simulations.","marker":"[21]"},{"why":"Defines the UrQMD hadronic afterburner and its resonance cross-sections, the switch that isolates hadronic-phase effects.","marker":"[37]"},{"why":"Provides resonance mean-free-path effects invoked to explain why $\\Lambda^{*}$ suppression is stronger than lifetime ordering alone would suggest.","marker":"[16]"}],"fun_headline_variants":["Hadronic phase lasts 0.5–1 fm/c even in high-multiplicity pp","EPOS4+UrQMD shows hadronic phase persists in high-multiplicity pp","Non-zero hadronic phase time measured in high-multiplicity pp via resonances","Resonance ratios reveal hadronic phase last longer with multiplicity","Hadronic phase lifetime at LHC: non-zero in high-multiplicity pp"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The extraction assumes that minimum-bias pp collisions have no hadronic rescattering, so their resonance-to-stable ratios stand in for the undamaged starting values, and if that reference system rescatters decay products, every extracted $\\tau$ is shifted.","fun_headline_variants_meta":{"raw":{"variants":["Hadronic phase lasts 0.5–1 fm/c even in high-multiplicity pp","EPOS4+UrQMD shows hadronic phase persists in high-multiplicity pp","Non-zero hadronic phase time measured in high-multiplicity pp via resonances","Resonance ratios reveal hadronic phase last longer with multiplicity","Hadronic phase lifetime at LHC: non-zero in high-multiplicity pp"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000799,"raw_usage":{"total_tokens":3606,"prompt_tokens":1127,"completion_tokens":2479,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":743,"completion_tokens_details":{"reasoning_tokens":2372}},"tokens_in":743,"tokens_out":2479,"duration_ms":18295,"temperature":1.0,"reasoning_tokens":2372,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-11T20:50:37.107199+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Run the same high-multiplicity pp events through EPOS4 with UrQMD turned off: if $K^{*0}/K$ no longer falls below the minimum-bias pp baseline, the non-zero $\\tau$ is a genuine afterburner effect, whereas if the suppression remains, the signal is produced before the hadronic phase and the exponential-decay interpretation would be wrong.","supporting_citations":[{"cited_title":"Production of K$^{*}(892)^{0}$ and $\\phi(1020)$ in pp and Pb-Pb collisions at $\\sqrt{s_{\\rm NN}} = 5.02$ TeV","cited_arxiv_id":"2106.13113","evidence_quote":"Provides high-multiplicity pp and p–Pb $K^{*0}/K$ suppression data that motivate a non-zero hadronic phase in small systems."},{"cited_title":"$\\mathrm{K}^{*}(\\mathrm{892})^{0}$ and $\\mathrm{\\phi(1020)}$ production in p-Pb collisions at $\\sqrt{s_{\\rm NN}}$ = 8.16 TeV","cited_arxiv_id":"2110.10042","evidence_quote":"Confirms the decreasing $K^{*0}/K$ trend in high-multiplicity small systems, strengthening the non-zero $\\tau$ conclusion."},{"cited_title":"Production of the $\\rho$(770)${^{0}}$ meson in pp and Pb-Pb collisions at $\\sqrt{s_{\\rm NN}}$ = 2.76 TeV","cited_arxiv_id":"1805.04365","evidence_quote":"Provides multiplicity-dependent $\\rho^0/\\pi$ and related resonance ratios used for the $\\tau$ estimate."},{"cited_title":"Werner, Phys","cited_arxiv_id":null,"evidence_quote":"Defines the EPOS4 core–corona and microcanonical hadronization framework used for all simulations."}],"review_version":1}