Pith. sign in

REVIEW 4 minor 34 references

First K*(892)0 data in central Ar+Sc show a multi-fm/c gap between freeze-outs that matches Pb+Pb at the top SPS energy.

Reviewed by Pith at T0; open to challenge. T0 means a machine referee read the full paper against a public rubric. the ladder, T0–T4 →

T0 review · grok-4.5

2026-07-11 05:16 UTC pith:EBC4XIP4

load-bearing objection Solid first K*(892)^0 data for central Ar+Sc at three SPS energies; freeze-out times extracted cleanly via the standard formula and look Pb+Pb-like at ~12–17 GeV.

arxiv 2607.05595 v1 pith:EBC4XIP4 submitted 2026-07-06 nucl-ex hep-ex

K^(*)(892)⁰ production and the time between freeze-outs in ⁴⁰Ar+⁴⁵Sc collisions by NA61/SHINE at the CERN SPS

classification nucl-ex hep-ex PACS 25.75.-q25.75.Dw25.75.Nq
keywords K*(892)0freeze-out timeAr+Sc collisionsSPS energiesresonance suppressionchemical freeze-outkinetic freeze-outNA61/SHINE
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper reports the first measurements of strange K*(892)0 resonance production in central argon-scandium collisions at three CERN SPS energies. Because the resonance lifetime is only a few fm/c, a sizable fraction of the particles decay while still inside the dense hadronic medium; elastic rescattering of the decay products then destroys the original invariant-mass signal. Comparing the observed K*/K yield ratios with those measured in proton-proton collisions therefore yields a lower limit on the time that elapses between chemical freeze-out (when particle species are fixed) and kinetic freeze-out (when elastic scatterings finally cease). The extracted intervals are consistent with zero at the lowest energy but rise to several fm/c at the two higher energies, becoming comparable to the values previously found for much heavier lead-lead systems. The result supplies a new intermediate-mass data point that constrains how the duration of the hadronic phase scales with system size and collision energy.

Core claim

In 0-10% central 40Ar+45Sc collisions the measured K*(892)0 / K ratios imply a time interval between chemical and kinetic freeze-outs that is significantly larger than zero and of similar magnitude to that of central Pb+Pb collisions at √sNN ≈ 17 GeV; at 8.8 GeV the same interval remains consistent with zero within uncertainties.

What carries the argument

The exponential survival formula K*/K|kinetic = K*/K|chemical imes exp(-Δt/τ), with the p+p ratio taken as the chemical value and τ = 4.17 fm/c, converts the observed resonance suppression into a Lorentz-boosted time gap γΔt.

Load-bearing premise

The method assumes that no regenerated K* mesons are produced after chemical freeze-out, so the extracted times are only lower limits on the true gap.

What would settle it

A measurement of the same K*/K ratios in an intermediate-mass system (for example Xe+La) at √sNN ≈ 17 GeV that yielded a freeze-out interval clearly different from both Ar+Sc and Pb+Pb would falsify the claimed system-size independence at top SPS energy.

Watch this falsifier — get emailed when new claim-graph text bears on it.

If this is right

  • The duration of the hadronic phase at top SPS energy does not grow strongly when the colliding system is enlarged from Ar+Sc to Pb+Pb.
  • Below roughly 10 GeV the hadronic phase in intermediate-mass systems becomes short enough that resonance suppression is no longer resolved.
  • Mean transverse momenta and inverse-slope parameters of K* rise with energy, consistent with increasing radial flow that further dilutes the reconstructed yield.
  • Future Xe+La data at the same energies will test whether the freeze-out gap continues to saturate or begins to scale again with system size.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • If regeneration is non-negligible, the true chemical-to-kinetic gap is longer than reported, strengthening the conclusion that intermediate-mass systems already develop a multi-fm/c hadronic phase at SPS energies.
  • The energy dependence mirrors the flat K*/K ratios seen in the RHIC Beam Energy Scan between 7.7 and 20 GeV, suggesting a common regime of nearly constant hadronic lifetime across a wide range of system sizes.
  • A simultaneous measurement of a longer-lived resonance (φ or Λ*) in the same Ar+Sc data set would provide an independent cross-check of the extracted time scale.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit.

Referee Report

0 major / 4 minor

Summary. This NA61/SHINE letter reports the first measurements of K*(892)^0 production in 0–10% central 40Ar+45Sc collisions at √sNN = 8.8, 11.9 and 16.8 GeV. Spectra in pT, mT and rapidity, together with mean multiplicities, are extracted via the K+π− channel using a template-method background subtraction, full GEANT4+EPOS/FTFP_BERT corrections, and branching-ratio and identification-efficiency factors. The resulting ⟨K*⟩/⟨K+⟩ and ⟨K*⟩/⟨K−⟩ ratios are compared with published p+p baselines and, via the standard exponential-suppression formula (Eq. 2), converted into lower-limit estimates of the time interval between chemical and kinetic freeze-outs. The extracted intervals are consistent with zero at 8.8 GeV and non-zero (and comparable to central Pb+Pb) at the two higher energies.

Significance. The work fills a genuine gap: intermediate-mass Ar+Sc systems at SPS energies had no prior K* data, so the system-size and energy dependence of the freeze-out interval could not be mapped between p+p and Pb+Pb. The analysis follows established NA61/SHINE procedures (template fit, PSD centrality, dual-MC systematics) and states its principal limitations (neglect of regeneration, identification of the p+p ratio with the chemical-freeze-out value) explicitly. The reported pattern—non-zero, Pb+Pb-like times at ≈12–17 GeV and a near-zero interval at 8.8 GeV—is therefore a clean, falsifiable first measurement that will be useful for transport-model and hydrodynamic comparisons.

minor comments (4)
  1. In Sec. 4 the inverse-slope parameters T are quoted with both statistical and systematic uncertainties, yet the text does not state whether the exponential fits were performed with statistical weights only or with total uncertainties; a one-sentence clarification would help reproducibility.
  2. Figure 3 (bottom right) shows γΔt values derived from both K+ and K− ratios; the caption and text could briefly note that the two determinations are consistent within uncertainties, so that the reader does not have to extract this by eye.
  3. The footnote on UrQMD (Sec. 4) is interesting but terse; a short remark on whether the model fails mainly on the absolute K*/K level or on the system-size dependence would strengthen the comparison without expanding the letter.
  4. A few typographical inconsistencies remain (e.g., “EUROPEAN ORGANISA TION”, occasional missing spaces around √sNN). These are easily cleaned in production.

Circularity Check

0 steps flagged

No significant circularity: Δt is a direct algebraic extraction from independently measured multiplicity ratios via a standard external formula.

full rationale

The paper's central result (time intervals between freeze-outs) is obtained by inserting newly measured ⟨K*(892)0⟩/⟨K±⟩ ratios for 0–10% central 40Ar+45Sc into the standard literature formula (Eq. 2) whose chemical-freeze-out baseline is taken from previously published, independent p+p data sets at comparable energies. No free parameters are fitted to the present yields and then re-used as predictions; the exponential suppression factor is evaluated once from the measured ratios and the known lifetime au. Self-citations (prior NA61/SHINE p+p analyses and the Ar+Sc charged-kaon paper) supply external numerical inputs, not load-bearing uniqueness theorems or ansatzes that force the reported pattern. The acknowledged neglect of regeneration is stated explicitly as rendering the intervals lower limits, not a hidden circular assumption. The derivation chain is therefore self-contained against external benchmarks and contains no reduction of a claimed prediction to its own inputs by construction.

Axiom & Free-Parameter Ledger

3 free parameters · 5 axioms · 0 invented entities

The central claim rests on measured yields, the external lifetime formula, and the conventional identification of p+p ratios with chemical freeze-out; free parameters are ordinary spectral-fit quantities used only for the Lorentz boost; no new dynamical entities are introduced.

free parameters (3)
  • inverse-slope parameters T of pT spectra = 226±17±19, 256±16±13, 284±21±19 MeV
    Fitted exponential slopes (226, 256, 284 MeV) describe the spectra and supply mean pT for the Lorentz factor γ; they do not enter the multiplicity ratios themselves.
  • mean transverse momenta ⟨pT⟩ used for γ = 685±34±40, 745±31±25, 801±41±38 MeV/c
    Extracted from the same pT fits and used solely to boost Δt into the lab frame; total uncertainties are propagated.
  • template-fit normalizations a, b, c
    Free scale factors in the invariant-mass fit (Eq. 1) that isolate the Breit-Wigner yield; varied as part of systematic uncertainty.
axioms (5)
  • domain assumption K*/K|kinetic = K*/K|chemical · exp(−Δt/τ) with τ = 4.17 fm/c
    Standard relation taken from Markert et al. (Eq. 2); used to convert measured ratios into a time interval.
  • domain assumption The K*/K ratio measured in inelastic p+p collisions equals the chemical-freeze-out ratio in the A+A system
    Explicit identification stated after Eq. 2; without it the exponential formula cannot be applied.
  • ad hoc to paper Regeneration of K*(892)^0 before kinetic freeze-out can be neglected
    Stated as a caveat that makes the extracted times lower limits only; if regeneration is large the true interval could be longer.
  • domain assumption Fixed PDG mass m0 = 895.55 MeV and width Γ = 47.3 MeV for the Breit-Wigner signal shape
    Used throughout the template fits; no free mass or width is floated.
  • domain assumption EPOS1.99 (and FTFP_BERT for systematics) correctly models acceptance, reconstruction efficiency and residual backgrounds
    Corrections are obtained by comparing generated and reconstructed Monte-Carlo events; model dependence is assessed by swapping generators.

pith-pipeline@v1.1.0-grok45 · 17105 in / 2774 out tokens · 46159 ms · 2026-07-11T05:16:12.778155+00:00 · methodology

0 comments
read the original abstract

The analysis of the production of strange $K^{*}(892)^0$ resonances allows us to better understand the temporal evolution of high-energy nucleus--nucleus collisions. In particular, the ratio of $K^{*}(892)^0$ to charged kaon yields is used to determine the time interval between chemical and kinetic freeze-outs. In this paper, the first measurements of $K^{*}(892)^0$ production in central $^{40}$Ar+$^{45}$Sc collisions at the CERN Super Proton Synchrotron are reported. They were performed by NA61/SHINE at collision center-of-mass energies per nucleon pair $\sqrt{s_\mathrm{NN}}$ = 8.8, 11.9, 16.8 GeV. The obtained $\langle K^{*}(892)^0 \rangle/\langle K^{+} \rangle $ and $\langle K^{*}(892)^0 \rangle/\langle K^{-} \rangle$ mean multiplicity ratios are compared with corresponding results in $p$+$p$ collisions, allowing for an estimate of the time interval between chemical and thermal freeze-outs in the $^{40}$Ar+$^{45}$Sc system. These are the first such results reported for $^{40}$Ar+$^{45}$Sc collisions.

Figures

Figures reproduced from arXiv: 2607.05595 by A. Blondel, A.D. Marino, A. Dmitriev, A.F. Camino, A.I. Malakhov, A. Krasnoperov, A. L\'aszl\'o, A. Marcinek, A. Olivier, A. Rustamov, A. Rybicki, A. Shukla, A. Tefelska, A. Wickremasinghe, A. Zaitsev, B.A. Popov, B. Koz{\l}owski, B. Maksiak, B. P\'orfy, C. Dalmazzone, D. Battaglia, D. Kolev, D. Pszczel, D. R\"ohrich, D. Rybka, D. Tefelski, D. Veberi\v{c}, E.D. Zimmerman, E. Zherebtsova, G.L. Melkumov, G. Lykasov, G. Stefanek, H. Shah, I. Pidhurskyi, J. Brzychczyk, J. Dumarchez, J.R. Lyon, J. Stepaniak, J. Szewi\'nski, K.E. Gollwitzer, K. Grebieszkow, K.K. Allison, K. Sakashita, K. Schmidt, K. Witek, K. W\'ojcik, L. Fields, {\L}. Mik, L. Ren, {\L}. Rozp{\l}ochowski, {\L}. \'Swiderski, L. Turko, M. Bajda, M. Bielewicz, M. Bogomilov, M. Buryakov, M. Csan\'ad, M. \'Cwiok, M. Friend, M. Ga\'zdzicki, M. Kuchowicz, M. Lewicki, M. Ma\'ckowiak-Paw{\l}owska, M. Roth, M. Rumyantsev, M. Rybczy\'nski, M. S{\l}odkowski, M. Unger, M. Urbaniak, NA61/SHINE Collaboration: P. Adrich, N. Davis, O. Panova, O. Vitiuk, P.G. Hurh, P. Lasko, P. Semeniuk, P. Staszel, P. von Doetinchem, R. Engel, R. Kolesnikov, R. Nagy, R. P{\l}aneta, R. Szukiewicz, R. Tsenov, S. Ilieva, S. Kowalski, S. Nishimori, S. Pu{\l}awski, T. Czopowicz, T. Kowalski, T. Matulewicz, T. Nakadaira, T. \v{S}u\v{s}a, U.A. Shah, V.A. Kireyeu, V. Golovatyuk, V. Matveev, V. Ozvenchuk, V. Paolone, V. Tereshchenko, V.V. Lyubushkin, V.Z. Reyna Ortiz, W. Dominik, W. Kucewicz, Y. Balkova, Y. Bondar, Y.D. Chandak, Y. Koshio, Y. Nagai, Y. Shiraishi, Z. Fodor.

Figure 1
Figure 1. Figure 1: Left: An example of invariant mass spectrum (blue dots) fitted with Eq. (1) (brown line, visible near the K ∗ (892) 0 resonance mass). The red line shows the fitted background estimated using the template method (reconstructed Monte Carlo from EPOS1.99 [24], as well as mixed events). Right: An invariant mass spectrum after fitted background subtraction. The red line is the residual background described by … view at source ↗
Figure 2
Figure 2. Figure 2: The transverse momentum (top left), transverse mass (top right), and rapidity (bottom left) spectra of K ∗ (892) 0 mesons produced in 0– 10% central 40Ar + 45Sc collisions at 40A, 75A, and 150A GeV/c ( √ sNN = 8.8, 11.9, 16.8 GeV). Bars de￾note statistical uncertainties, color bands or boxes – systematic ones. The three panels of [PITH_FULL_IMAGE:figures/full_fig_p006_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: The system size dependencies (⟨NW⟩ corresponds to the mean number of wounded nucleons) of ⟨K ∗ (892) 0 ⟩/⟨K +⟩ and ⟨K ∗ (892) 0 ⟩/⟨K −⟩ratios (⟨K +/−⟩ on vertical axes denote ⟨K +⟩ or⟨K −⟩) at√ sNN = 8.8 GeV, √ sNN ≈ 12 GeV, and √ sNN ≈ 17 GeV (top and bottom left) as well as the energy dependence of time be￾tween freeze-outs (bottom right). Plots include the NA61/SHINE results on K ∗ (892) 0 production in… view at source ↗

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

34 extracted references · 16 canonical work pages · 14 internal anchors

  1. [1]

    R. D. PisarskiPhys. Lett. B110(1982) 155–158

  2. [2]

    G. E. Brown and M. RhoPhys. Rev. Lett.66(1991) 2720–2723

  3. [3]

    G. E. Brown and M. RhoPhys. Rept.269(1996) 333–380,arXiv:hep-ph/9504250

  4. [4]

    Light Vector Mesons

    A. MilovEur. Phys. J. C61(2009) 721–728,arXiv:0809.3880 [nucl-ex]

  5. [5]

    Schnedermann, J

    E. Schnedermann, J. Sollfrank, and U. W. HeinzPhys. Rev. C48(1993) 2462–2475, arXiv:nucl-th/9307020

  6. [6]

    Becattini, J

    F. Becattini, J. Manninen, and M. Ga´ zdzickiPhys. Rev. C73(2006) 044905, arXiv:hep-ph/0511092

  7. [7]

    Strange Hadron Resonances: Freeze-Out Probes in Heavy-Ion Collisions

    C. Markert, G. Torrieri, and J. RafelskiAIP Conf. Proc.631no. 1, (2002) 533, arXiv:hep-ph/0206260

  8. [8]

    Navaset al., [Particle Data Group Collab.]Phys

    S. Navaset al., [Particle Data Group Collab.]Phys. Rev. D110(2024) 030001

  9. [9]

    $K^{*}(892)^0$ meson production in inelastic p+p interactions at 158 GeV/$c$ beam momentum measured by NA61/SHINE at the CERN SPS

    A. Aduszkiewiczet al., [NA61/SHINE Collab.]Eur. Phys. J. C80no. 5, (2020) 460, arXiv:2001.05370 [nucl-ex]

  10. [10]

    Abdallahet al., [STAR Collab.]Phys

    M. Abdallahet al., [STAR Collab.]Phys. Rev. C107no. 3, (2023) 034907,arXiv:2210.02909 [nucl-ex]. 9

  11. [11]

    A. K. SahooActa Phys. Polon. Supp.16no. 1, (2023) 1–A132,arXiv:2209.04863 [hep-ex]

  12. [12]

    System size dependence of the hadronic rescattering effect at energies available at the CERN Large Hadron Collider

    S. Acharyaet al., [ALICE Collab.]Phys. Rev. C109no. 1, (2024) 014911,arXiv:2308.16115 [nucl-ex]

  13. [13]

    S. K. Daset al. Int. J. Mod. Phys. E31(2022) 12,arXiv:2208.13440 [nucl-th]

  14. [14]

    $K^{*}(892)^0$ meson production in inelastic $p+p$ interactions at 40 and 80 GeV/$c$ beam momenta measured by NA61/SHINE at the CERN SPS

    A. Acharyaet al., [NA61/SHINE Collab.]Eur. Phys. J. C82no. 4, (2022) 322, arXiv:2112.09506 [nucl-ex]

  15. [15]
  16. [16]

    Measurements of $\pi^\pm$, $K^\pm$, $p$ and $\bar{p}$ spectra in $^{40}$Ar+$^{45}$Sc collisions at 13$A$ to 150$A$ GeV/$c$

    H. Adhikaryet al., [NA61/SHINE Collab.]Eur. Phys. J. C84no. 4, (2024) 416, arXiv:2308.16683 [nucl-ex]

  17. [17]

    Abgrallet al., [NA61 Collab.]JINST9(2014) P06005,arXiv:1401.4699 [physics.ins-det]

    N. Abgrallet al., [NA61 Collab.]JINST9(2014) P06005,arXiv:1401.4699 [physics.ins-det]

  18. [18]
  19. [19]

    Adhikaryet al., [NA61/SHINE Collab.]Eur

    H. Adhikaryet al., [NA61/SHINE Collab.]Eur. Phys. J. C83no. 9, (2023) 881, arXiv:2305.07557 [nucl-ex]

  20. [20]

    Adhikaryet al., [NA61/SHINE Collab.]Eur

    H. Adhikaryet al., [NA61/SHINE Collab.]Eur. Phys. J. C84no. 7, (2024) 741, arXiv:2401.03445 [nucl-ex]

  21. [21]

    Adhikaryet al., [NA61/SHINE Collab.]Eur

    H. Adhikaryet al., [NA61/SHINE Collab.]Eur. Phys. J. C85no. 8, (2025) 918, arXiv:2503.22484 [nucl-ex]

  22. [22]

    Kozłowski, PhD thesis, Warsaw University of Technology, 2025, https://doi.org/10.17181/svcvw-my697

    B. Kozłowski, PhD thesis, Warsaw University of Technology, 2025, https://doi.org/10.17181/svcvw-my697

  23. [23]

    PSD acceptance maps,https://edms.cern.ch/document/1867336/1

  24. [24]

    Werner, F.-M

    K. Werner, F.-M. Liu, and T. PierogPhys. Rev. C74(2006) 044902,arXiv:hep-ph/0506232

  25. [25]

    Agostinelliet al., [GEANT4 Collab.]Nucl

    S. Agostinelliet al., [GEANT4 Collab.]Nucl. Instrum. Meth. A506(2003) 250–303

  26. [26]

    Allisonet al

    J. Allisonet al. Nucl. Instrum. Meth. A835(2016) 186–225

  27. [27]
  28. [28]

    $K^*(892)$ Resonance Suppression in Ar+Sc Collisions at SPS Energies

    A. Chabane, T. Reichert, J. Steinheimer, and M. BleicherPhys. Rev. C113no. 5, (2026) 055202, arXiv:2509.07568 [nucl-th]

  29. [29]

    Adamset al., [STAR Collab.]Phys

    J. Adamset al., [STAR Collab.]Phys. Rev. C71(2005) 064902,arXiv:nucl-ex/0412019

  30. [30]

    Acharyaet al., [ALICE Collab.]Phys

    S. Acharyaet al., [ALICE Collab.]Phys. Lett. B802(2020) 135225,arXiv:1910.14419 [nucl-ex]

  31. [31]

    B. E. Aboonaet al., [STAR Collab.]Phys. Lett. B876(2026) 140389,arXiv:2601.14884 [nucl-ex]

  32. [32]

    $K^{\ast}(892)^0$ and $\bar{K}^{\ast}(892)^0$ production in central Pb+Pb, Si+Si, C+C and inelastic p+p collisions at 158$A$~GeV

    T. Anticicet al., [NA49 Collab.]Phys. Rev. C84(2011) 064909,arXiv:1105.3109 [nucl-ex]

  33. [33]

    System-size dependence of strangeness production in nucleus-nucleus collisions at sqrt{s_{NN}}=17.3 GeV

    C. Altet al., [NA49 Collab.]Phys. Rev. Lett.94(2005) 052301,arXiv:nucl-ex/0406031

  34. [34]

    S. V . Afanasievet al., [NA49 Collab.]Phys. Rev. C66(2002) 054902,arXiv:nucl-ex/0205002. 10 The NA61/SHINE Collaboration P. Adrich 13, K.K. Allison 23, M. Bajda 14, Y . Balkova 13, D. Battaglia 22, M. Bielewicz 13, A. Blondel 4, M. Bogomilov 2, Y . Bondar 11, J. Brzychczyk 14, M. Buryakov 20, A.F. Camino25, Y .D. Chandak 23, M. Csanád 7, M. ´Cwiok 17, T. ...