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Exploring strangeness enhancement and particle production in small collision systems with EPOS4 at sNN =5.02  TeV

Hirak Kumar Koley1,*, Subikash Choudhury1,†, Argha Deb1,2,‡, and Mitali Mondal1,2,§

  • 1Nuclear and Particle Physics Research Centre, Department of Physics, Jadavpur University, Kolkata 700032, India
  • 2School of Studies in Environmental Radiation and Archaeological Sciences, Jadavpur University, Kolkata 700032, India

  • *Contact author: hirak.koley@gmail.com
  • †Contact author: subikash.choudhury@gmail.com
  • ‡Contact author: argha_deb@yahoo.com
  • §Contact author: mitalimon@gmail.com
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Phys. Rev. D 112, 054034 – Published 22 September, 2025

DOI: https://doi.org/10.1103/lm22-tmqr

Abstract

The observation of collectivity and strangeness enhancement in small collision systems, such as proton-proton (pp) and proton-lead (p-Pb) collisions, challenges traditional assumptions regarding thermalization and particle production mechanisms. In this study, we investigate particle yields and transverse momentum distributions in pp and p-Pb collisions at sNN=5.02  TeV using the EPOS4 event generator, which employs a core-corona framework to model particle production across a variety of system sizes. EPOS4 successfully reproduces many qualitative trends observed in experimental data, including the hardening of pT spectra with multiplicity, the hierarchical strangeness enhancement in strange-to-pion ratios, and characteristic modifications of particle yield ratios as a function of pT and multiplicity. The microcanonical approach to core hadronization used in EPOS4 seems to provide a more realistic description of small systems compared to grand-canonical treatments. Nonetheless, quantitative discrepancies still persist in describing several physical observables. Future model refinements, including improved core-corona balancing, differential freeze-out conditions for multistrange hadrons, and incorporation of finite strangeness correlation volumes, may be taken into account for enhancing EPOS4’s predictive power and deepening our understanding of the complex dynamics governing the particle production in high-energy collisions.

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Phys. Rev. D 112, 054034– Published 22 September, 2025
  • Received 16 June 2025
  • Accepted 26 August 2025
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