$\mathbf{{\textbf{K}}^{0}_{\textbf{S}}}-\mathbf{{\textbf{K}}^{0}_{\textbf{S}}}$ femtoscopy in Pb$-$Pb collisions at $\mathbf{\sqrt{\textit{s}_{\rm NN}} = 5.02}$ TeV at the LHC

TL;DR

This paper presents a femtoscopic analysis of K0s-K0s correlations in Pb-Pb collisions at 5.02 TeV, revealing insights into the source size and collective behavior, with comparisons to models and other experiments.

Contribution

First femtoscopic measurement of K0s-K0s correlations at 5.02 TeV, extending previous studies and testing hydrodynamic models at higher energies.

Findings

Source radii decrease with increasing pair transverse momentum.

Results are consistent with collective expansion of the system.

Hydrokinetic models match central but not peripheral collision data.

Abstract

Results from a one-dimensional femtoscopic analysis of ${\rm K}^{0}_{\rm S}-{\rm K}^{0}_{\rm S}$ correlations in Pb$-$Pb collisions at the center-of-mass energy $\sqrt{s_{\mathrm{NN}}}~=~5.02$ TeV using data collected by the ALICE experiment at the LHC are presented. The source radius $R$ and correlation strength $\lambda$ are studied as a function of centrality and pair-transverse momentum ($k_{\rm T}$) to provide insight into the space-time structure and composition of the particle-emitting source. The observed trends of radii as a function of $k_{\rm T}$ and centrality are consistent with the collective expansion of the system. Comparisons with measurements at $\sqrt{s_{\mathrm{NN}}}~=~2.76$ TeV by the ALICE Collaboration show agreement across multiplicities and $k_{\rm T}$. Hydrokinetic model predictions match the most central collision results but deviate in peripheral events, potentially reflecting limitations in the model's description of peripheral collisions. A comparison with recent measurements at the same energy by the CMS Collaboration shows compatibility in both $R$ and $\lambda$ within 1.3$\sigma$. These results extend previous ${\rm K}^{0}_{\rm{S}}-{\rm K}^{0}_{\rm{S}}$ femtoscopy to a higher energy, providing a consistent baseline for future comparisons.