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Quark flavor equilibration of the quark-gluon plasma

Andrew Gordeev1, Steffen A. Bass1, Berndt Müller1, and Jean-François Paquet2

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Phys. Rev. C 113, 014906 – Published 12 January, 2026

DOI: https://doi.org/10.1103/w7tz-mlh7

Abstract

The early stage of a heavy-ion collision is marked by rapid entropy production and the transition from a gluon saturated initial condition to a plasma of quarks and gluons that evolves hydrodynamically. However, during the early times of the hydrodynamic evolution, the chemical composition of the QCD medium is still largely unknown. We present a study of quark chemical equilibration in the (Q)GP using a novel model of viscous hydrodynamic evolution in partial chemical equilibrium. Motivated by the success of gluon saturated initial condition models, we initialize the QCD medium as a completely gluon dominated state. Local quark production during the hydrodynamic phase is then simulated through the evolution of time-dependent fugacities for each independent quark flavor, with the timescales set as free parameters to compare different rates of equilibration. We present the results of complete heavy-ion collision simulations using this partial chemical equilibrium model, and show the effects on hadronic and electromagnetic observables. In particular, we show that the development of flow is sensitive to the equilibration timescale, providing an empirical way to probe the chemical equilibration of the QCD medium.

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References (55)

  1. B. Schenke, P. Tribedy, and R. Venugopalan, Phys. Rev. Lett. 108, 252301 (2012).
  2. K. J. Eskola, K. Kajantie, P. V. Ruuskanen, and K. Tuominen, Nucl. Phys. B 570, 379 (2000).
  3. L. D. McLerran and R. Venugopalan, Phys. Rev. D 49, 2233 (1994).
  4. L. V. Gribov, E. M. Levin, and M. G. Ryskin, Phys. Rept. 100, 1 (1983).
  5. F. Gelis, E. Iancu, J. Jalilian-Marian, and R. Venugopalan, Annu. Rev. Nucl. Part. Sci. 60, 463 (2010).
  6. R. Baier, A. H. Mueller, D. Schiff, and D. T. Son, Phys. Lett. B 502, 51 (2001).
  7. E. V. Shuryak, Phys. Rev. Lett. 68, 3270 (1992).
  8. T. S. Biro, E. van Doorn, B. Muller, M. H. Thoma, and X. N. Wang, Phys. Rev. C 48, 1275 (1993).
  9. A. El, Z. Xu, and C. Greiner, Nucl. Phys. A 806, 287 (2008).
  10. A. Kurkela and Y. Zhu, Phys. Rev. Lett. 115, 182301 (2015).
  11. L. Keegan, A. Kurkela, A. Mazeliauskas, and D. Teaney, J. High Energy Phys. 08 (2016) 171.
  12. A. Kurkela, A. Mazeliauskas, J.-F. Paquet, S. Schlichting, and D. Teaney, Phys. Rev. C 99, 034910 (2019).
  13. T. Epelbaum and F. Gelis, Phys. Rev. Lett. 111, 232301 (2013).
  14. J. Berges, K. Boguslavski, S. Schlichting, and R. Venugopalan, Phys. Rev. D 89, 114007 (2014).
  15. B. Schenke, S. Schlichting, and R. Venugopalan, Phys. Lett. B 747, 76 (2015).
  16. Z. Xu and C. Greiner, Phys. Rev. C 71, 064901 (2005).
  17. A. Kurkela and A. Mazeliauskas, Phys. Rev. D 99, 054018 (2019).
  18. A. Kurkela and A. Mazeliauskas, Phys. Rev. Lett. 122, 142301 (2019).
  19. V. Vovchenko, M. I. Gorenstein, L. M. Satarov, I. N. Mishustin, L. P. Csernai, I. Kisel, and H. Stöcker, Phys. Rev. C 93, 014906 (2016).
  20. V. Vovchenko, I. A. Karpenko, M. I. Gorenstein, L. M. Satarov, I. N. Mishustin, B. Kämpfer, and H. Stoecker, Phys. Rev. C 94, 024906 (2016).
  21. G. S. Denicol, H. Niemi, E. Molnar, and D. H. Rischke, Phys. Rev. D 85, 114047 (2012); 91, 039902(E) (2015).
  22. E. Molnár, H. Niemi, G. S. Denicol, and D. H. Rischke, Phys. Rev. D 89, 074010 (2014).
  23. G. S. Denicol, S. Jeon, and C. Gale, Phys. Rev. C 90, 024912 (2014).
  24. A. Bazavov, et al., Phys. Rev. D 95, 054504 (2017).
  25. A. Bazavov, et al. (HotQCD Collaboration), Phys. Rev. D 90, 094503 (2014).
  26. S. Borsanyi, G. Endrodi, Z. Fodor, S. D. Katz, and K. K. Szabo, J. High Energy Phys. 07 (2012) 056.
  27. P. Moreau (private communication).
  28. F. Burger, E.-M. Ilgenfritz, M. Kirchner, M. P. Lombardo, M. Müller-Preussker, O. Philipsen, C. Urbach, and L. Zeidlewicz (tmfT Collaboration), Phys. Rev. D 87, 074508 (2013).
  29. V. G. Bornyakov, R. Horsley, S. M. Morozov, Y. Nakamura, M. I. Polikarpov, P. E. L. Rakow, G. Schierholz, and T. Suzuki, Phys. Rev. D 82, 014504 (2010).
  30. P. Huovinen and P. Petreczky, Nucl. Phys. A 837, 26 (2010).
  31. H. Stoecker, et al., J. Phys. G 43, 015105 (2016).
  32. H. B. Meyer, Phys. Rev. D 80, 051502 (2009).
  33. F. Cooper and G. Frye, Phys. Rev. D 10, 186 (1974).
  34. P. Huovinen and H. Petersen, Eur. Phys. J. A 48, 171 (2012).
  35. H. Grad, Commun. Pure Appl. Math. 2, 331 (1949).
  36. A. Monnai and T. Hirano, Phys. Rev. C 80, 054906 (2009).
  37. M. McNelis and U. Heinz, Phys. Rev. C 103, 064903 (2021).
  38. J. S. Moreland, J. E. Bernhard, and S. A. Bass, Phys. Rev. C 92, 011901 (2015).
  39. B. Schenke, S. Jeon, and C. Gale, Phys. Rev. C 82, 014903 (2010).
  40. B. Schenke, S. Jeon, and C. Gale, Phys. Rev. Lett. 106, 042301 (2011).
  41. J.-F. Paquet, C. Shen, G. S. Denicol, M. Luzum, B. Schenke, S. Jeon, and C. Gale, Phys. Rev. C 93, 044906 (2016).
  42. D. Everett, et al. (JETSCAPE Collaboration), Phys. Rev. Lett. 126, 242301 (2021).
  43. M. McNelis, D. Everett, and U. Heinz, Comput. Phys. Commun. 258, 107604 (2021).
  44. J. Weil, et al. (SMASH Collaboration), Phys. Rev. C 94, 054905 (2016).
  45. B. Abelev, et al. (ALICE Collaboration), Phys. Rev. C 88, 044910 (2013).
  46. J. Steinheimer, J. Aichelin, and M. Bleicher, Phys. Rev. Lett. 110, 042501 (2013).
  47. I. A. Karpenko, Y. M. Sinyukov, and K. Werner, Phys. Rev. C 87, 024914 (2013).
  48. F. Becattini, M. Bleicher, T. Kollegger, T. Schuster, J. Steinheimer, and R. Stock, Phys. Rev. Lett. 111, 082302 (2013).
  49. H. Song and U. W. Heinz, Phys. Rev. C 77, 064901 (2008).
  50. C. Shen and U. Heinz, Phys. Rev. C 83, 044909 (2011).
  51. K. Dusling and T. Schäfer, Phys. Rev. C 85, 044909 (2012).
  52. S. Ryu, J.-F. Paquet, C. Shen, G. Denicol, B. Schenke, S. Jeon, and C. Gale, Phys. Rev. C 97, 034910 (2018).
  53. P. B. Arnold, G. D. Moore, and L. G. Yaffe, J. High Energy Phys. 12 (2001) 009.
  54. J. Rafelski and B. Müller, Phys. Rev. Lett. 48, 1066 (1982); 56, 2334(E) (1986).
  55. A. Dumitru, S. A. Bass, M. Bleicher, H. Stoecker, and W. Greiner, Phys. Lett. B 460, 411 (1999).

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Phys. Rev. C 113, 014906– Published 12 January, 2026
  • Received 8 February 2025
  • Revised 1 September 2025
  • Accepted 23 October 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.

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