Centrality dependence of strange particle production in Pb-Pb collisions at (Formula presented)

Abstract

The centrality dependence of strange (KS0, Λ+ Λ) and multistrange (Ξ−+ Ξ+, Ω−+ Ω+) hadron production is measured by ALICE in the Large Hadron Collider (LHC) lead-lead (Pb-Pb) collisions at a center-of-mass energy per nucleon pair √sNN = 5.02 TeV, using the full dataset collected during the LHC Run 2 campaign in the years 2015 and 2018. This is the largest heavy-ion dataset analyzed to date at the LHC, and it allows for the extraction of transverse momentum (pT) spectra and pT-integrated yields with unprecedented precision, over a broad range of charged particle multiplicity densities (〈dNch/dη〉|η|<0.5), probing regions where smaller collision system (pp and p-Pb) results are also available. The pT spectra evolve with centrality, featuring higher 〈pT〉 in central events for all particles. The Λ/KS0 ratio exhibits the distinctive baryon-to-meson enhancement in the intermediate pT region, with a maximum which is shifted to larger pT for more central collisions. The hadron-to-pion yield ratios are presented as a function of 〈dNch/dη〉|η|<0.5 and compared to results from different collision systems and energies. A smooth connection from pp to Pb-Pb is observed, thus demonstrating that collision system or energy do not play a role in the multiplicity evolution of this observable. The previously reported enhancement of strangeness production in the multiplicity range probed in pp and p-Pb collisions saturates in the multiplicity range of Pb-Pb data. These results constitute a key test bench for theoretical models and a first comparison to the EPOS 4 generator is presented. © 2026 CERN, for the ALICE Collaboration