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Hadronization impact on J/ψ energy correlators: A pythia8 study from partonic to hadronic observables

Jin-Peng Zhang1, Qian Yang2,*, Wen-Chao Zhang1,†, and Yu-jiao Zhao2

  • 1School of Physics and Information Technology, Shaanxi Normal University, Xi’an 710119, China
  • 2Institute of Frontier and Interdisciplinary Science, Key Laboratory of Particle Physics and Particle Irradiation (MOE), Shandong University, (QingDao), Shandong 266237, China

  • *Contact author: yangqian2020@sdu.edu.cn
  • †Contact author: wenchao.zhang@snnu.edu.cn
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Phys. Rev. D 113, 054038 – Published 24 March, 2026

DOI: https://doi.org/10.1103/b777-6n2y

Abstract

A comprehensive study of the J/ψ energy correlator as a probe of nonperturbative hadronization in color-octet cc¯ production is performed. The energy correlator measures the energy flow as a function of the angular distance (χ) from the identified J/ψ meson. Using the pythia8 Monte Carlo event generator, the correlator is computed at both parton and hadron levels. At high-J/ψ transverse momentum (pT>7  GeV/c), the parton-level correlator in the cosχ>0 region is dominated by soft gluon emission during the hadronization of the color-octet state, a contribution clearly distinguishable from other partonic sources, such as underlying multiparton interactions. The transition to the hadron level, however, introduces substantial modifications, suppressing the correlator in this region by approximately an order of magnitude and underscoring the complexity of the hadronization mapping. Further analysis reveals that the hadron-level observable exhibits notable sensitivity to model parameters: increasing the mass splitting between colored cc¯ pre-resonances and the J/ψ meson from 0.2 to 0.8  GeV/c2 enhances the correlator by up to 60%, while extending the color reconnection range yields a milder enhancement of about 10%. These findings demonstrate that precise measurements of the hadron-level J/ψ energy correlator, when interpreted within robust event-generator frameworks, can provide novel constraints on hadronization dynamics and help clarify the production mechanisms of the J/ψ state.

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References (46)

  1. N. Brambilla et al., Heavy quarkonium: Progress, puzzles, and opportunities, Eur. Phys. J. C 71, 1534 (2011).
  2. E. Braaten and J. Russ, J/ψ and ϒ polarization in hadronic production processes, Annu. Rev. Nucl. Part. Sci. 64, 221 (2014).
  3. M. Krämer, Quarkonium production at high-energy colliders, Prog. Part. Nucl. Phys. 47, 141 (2001).
  4. M. B. Einhorn and S. D. Ellis, Hadronic production of the new resonances: Probing gluon distributions, Phys. Rev. D 12, 2007 (1975).
  5. M. Butenschoen and B. A. Kniehl, World data of J/ψ production consolidate nonrelativistic QCD factorization at next-to-leading order, Phys. Rev. D 84, 051501 (2011).
  6. K.-T. Chao, Y.-Q. Ma, H.-S. Shao, K. Wang, and Y.-J. Zhang, J/ψ polarization at hadron colliders in nonrelativistic QCD, Phys. Rev. Lett. 108, 242004 (2012).
  7. B. Gong, L.-P. Wan, J.-X. Wang, and H.-F. Zhang, Polarization for prompt J/ψ and ψ(2s) production at the Tevatron and LHC, Phys. Rev. Lett. 110, 042002 (2013).
  8. G. T. Bodwin, H. S. Chung, U.-R. Kim, and J. Lee, Fragmentation contributions to J/ψ production at the tevatron and the LHC, Phys. Rev. Lett. 113, 022001 (2014).
  9. Y.-Q. Ma and R. Vogt, Quarkonium production in an improved color evaporation model, Phys. Rev. D 94, 114029 (2016).
  10. H. Fritzsch, Producing heavy quark flavors in hadronic collisions’ A test of quantum chromodynamics, Phys. Lett. B 67, 217 (1977).
  11. S. P. Baranov and A. V. Lipatov, Prompt Charmonia production and polarization at the LHC in the NRQCD with kT-factorization. III. J/ψ meson, Phys. Rev. D 96, 034019 (2017).
  12. M. Siddikov and I. Schmidt, Exclusive production of quarkonia pairs in collinear factorization framework, Phys. Rev. D 107, 034037 (2023).
  13. K.-F. Ye, Q. Wang, J.-H. Shi, Z.-Y. Qin, W.-C. Zhang, A.-K. Lei, Z.-L. She, Y.-L. Yan, and B.-H. Sa, Energy dependence of J/ψ production in pp collisions from the PACIAE model, Phys. Rev. C 109, 035201 (2024).
  14. J.-P. Zhang, G.-Y. Wang, W.-C. Zhang, B. Feng, A.-K. Lei, Z.-L. She, H. Zheng, D.-M. Zhou, Y.-L. Yan, and B.-H. Sa, Inclusive J/ψ productions in pp collisions at s=5.02, 7, and 13 TeV with the PACIAE model, arXiv:2511.14105.
  15. Belle Collaboration, Measurement of the e+e−→J/ψ cc¯ cross section at s=10.6  GeV, Phys. Rev. D 79, 071101 (2009).
  16. NuSea Collaboration, J/ψ polarization in 800-GeV p-Cu interactions, Phys. Rev. Lett. 91, 211801 (2003).
  17. HERA-B Collaboration, Angular distributions of leptons from J/ψ’s produced in 920 GeV fixed-target proton-nucleus collisions, Eur. Phys. J. C 60, 517 (2009).
  18. CDF Collaboration, J/ψ and ψ(2S) production in pp¯ collisions at s=1.8  TeV, Phys. Rev. Lett. 79, 572 (1997).
  19. CDF Collaboration, Measurement of J/ψ and ψ(2S) polarization in pp¯ collisions at s=1.8  TeV, Phys. Rev. Lett. 85, 2886 (2000).
  20. DØ Collaboration, J/ψ production in pp collisions at s=1.8  TeV, Phys. Lett. B 370, 239 (1996).
  21. STAR Collaboration, Measurements of the transverse-momentum-dependent cross sections of J/ψ production at mid-rapidity in proton+proton collisions at s=510 and 500 GeV with the Star detector, Phys. Rev. D 100, 052009 (2019).
  22. PHENIX Collaboration, Ground and excited state charmonium production in p+p collisions at s=200  GeV, Phys. Rev. D 85, 092004 (2012).
  23. PHENIX Collaboration, Transverse momentum dependence of J/ψ polarization at midrapidity in p+p collisions at s=200  GeV, Phys. Rev. D 82, 012001 (2010).
  24. STAR Collaboration, J/ψ polarization in p+p collisions s=200  GeV in star, Phys. Lett. B 739, 180 (2014).
  25. STAR Collaboration, Measurement of inclusive J/ψ polarization in p+p collisions at s=200  GeV by the Star experiment, Phys. Rev. D 102, 092009 (2020).
  26. LHCb Collaboration, Measurement of J/ψ production in pp collisions at s=200  GeV, Eur. Phys. J. C 71, 1645 (2011).
  27. ALICE Collaboration, Measurement of inclusive J/ψ pair production cross section in pp collisions at s=13  TeV, Phys. Rev. C 108, 045203 (2023).
  28. ATLAS Collaboration, Measurement of the differential cross-sections of prompt and non-prompt production of J/ψ and ψ(2S) in pp collisions at s=7 and 8 TeV with the ATLAS detector, Eur. Phys. J. C 76, 283 (2016).
  29. ATLAS Collaboration, Measurement of Upsilon production in 7 TeV pp collisions at ATLAS, Phys. Rev. D 87, 052004 (2013).
  30. ALICE Collaboration, J/ψ polarization in pp collisions at s=7  TeV, Phys. Rev. Lett. 108, 082001 (2012).
  31. CMS Collaboration, Measurement of the prompt J/ψ and ψ(2s) polarizations in pp collisions at s=7  TeV, Phys. Lett. B 727, 381 (2013).
  32. H. S. Shao, H. Han, Y. Q. Ma, C. Meng, Y. J. Zhang, and K. T. Chao, Yields and polarizations of prompt J/ψ and ψ(2S) production in hadronic collisions, J. High Energy Phys. 05 (2015) 103.
  33. M. Butenschoen and B. A. Kniehl, J/ψ polarization at the Tevatron and the LHC: Nonrelativistic-QCD factorization at the crossroads, Phys. Rev. Lett. 108, 172002 (2012).
  34. A.-P. Chen, X. Liu, and Y.-Q. Ma, Shedding light on hadronization by quarkonium energy correlator, Phys. Rev. Lett. 133, 191901 (2024).
  35. T. Sjöstrand, S. Mrenna, and P. Skands, A brief introduction to pythia8.1, Comput. Phys. Commun. 178, 852 (2008).
  36. T. Sjöstrand, S. Ask, J. R. Christiansen, R. Corke, N. Desai, P. Ilten, S. Mrenna, S. Prestel, C. O. Rasmussen, and P. Z. Skands, An introduction to pythia8.2, Comput. Phys. Commun. 191, 159 (2015).
  37. Christian Bierlich, Smita Chakraborty et al., A comprehensive guide to the physics and usage of pythia8.3, SciPost Phys. Codebases 2022, 8 (2022).
  38. B. Sahoo, D. Sahu, S. Deb, C. R. Singh, and R. Sahoo, J/ψ and ψ(2s) polarization in proton-proton collisions at energies available at the Cern Large Hadron Collider using pythia8, Phys. Rev. C 109, 034910 (2024).
  39. D. Thakur, S. De, R. Sahoo, and S. Dansana, Role of multiparton interactions on J/ψ production in p+p collisions at LHC energies, Phys. Rev. D 97, 094002 (2018).
  40. C. Bierlich, P. Ilten, T. Menzo, S. Mrenna, M. Szewc, M. K. Wilkinson, A. Youssef, and J. Zupan, Reweighting Monte Carlo predictions and automated fragmentation variations in pythia8, SciPost Phys. 16, 134 (2024).
  41. P. Z. Skands, Tuning Monte Carlo generators: The Perugia tunes, Phys. Rev. D 82, 074018 (2010).
  42. P. Skands, S. Carrazza, and J. Rojo, Tuning P8.1: The Monash 2013 tune, Eur. Phys. J. C 74, 3024 (2014).
  43. A. M. Sirunyan et al., Extraction and validation of a new set of CMS pythia8 tunes from underlying-event measurements, Eur. Phys. J. C 80, 4 (2020).
  44. P. Gunnellini, H. Jung, and R. Maharucksit, Investigation of the energy dependence of the pT0 parameter in the pythia8 Monte Carlo event generator, Eur. Phys. J. C 78, 521 (2018).
  45. M. R. Aguilar, Z. Chang, R. K. Elayavalli, R. Fatemi, Y. He, Y. Ji, D. Kalinkin, M. Kelsey, I. Mooney, and V. Verkest, pythia8 underlying event tune for RHIC energies, Phys. Rev. D 105, 016011 (2022).
  46. M. R. Masouminia and P. Richardson, Quarkonium parton shower in Herwig 7, arXiv:2508.06307.

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Phys. Rev. D 113, 054038– Published 24 March, 2026
  • Received 9 January 2026
  • Accepted 4 March 2026
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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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