Centrality dependence of strange particle production in Pb-Pb collisions at $\sqrt{s_{\mathrm{N}\mathrm{N}}}=5.02$ TeV

The centrality dependence of strange ($K_S^0$, $\mathrm{\Lambda }+\bar{\mathrm{\Lambda }}$) and multi-strange (${\mathrm{\Xi }}^{-}+\overline{{\mathrm{\Xi }}^{+}}$, ${\mathrm{\Omega }}^{-}+{\bar{\mathrm{\Omega }}}^{+}$) hadron production is measured by ALICE in the LHC lead-lead (Pb-Pb) collisions at a center-of-mass energy per nucleon pair $\sqrt{s_{\mathrm{N}\mathrm{N}}}=5.02$~TeV, using the full data set collected during the LHC Run 2 campaign in the years 2015 and 2018. This is the largest heavy-ion data set analyzed to date at the LHC, and it allows for the extraction of transverse momentum ($p_T$) spectra and $p_T$-integrated yields with unprecedented precision, over a broad range of charged particle multiplicity densities ($⟨d{N}_{ch}\mathrm{/}d\eta {⟩}_{\mathrm{\mid }\eta \mathrm{\mid }<0.5}$), probing regions where smaller collision system (pp and p-Pb) results are also available. The $p_T$ spectra evolve with centrality, featuring higher $⟨p_T⟩$ in central events for all particles. The $\mathrm{\Lambda }\mathrm{/}{K}_S^0$ ratio exhibits the distinctive baryon-to-meson enhancement in the intermediate $p_T$ region, with a maximum which is shifted to larger $p_T$ for more central collisions. The hadron-to-pion yield ratios are presented as a function of $⟨d{N}_{ch}\mathrm{/}d\eta {⟩}_{\mathrm{\mid }\eta \mathrm{\mid }<0.5}$ 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.