Non-identical particle femtoscopy in Pb--Pb collisions at 5.02 TeV with ALICE

TL;DR

This paper uses non-identical particle femtoscopy to measure the size and emission asymmetry of particle sources in Pb--Pb collisions at 5.02 TeV, revealing system collectivity and its dependence on multiplicity and transverse momentum.

Contribution

It presents the first femtoscopic analysis of pion-kaon pairs in Pb--Pb collisions at 5.02 TeV using spherical harmonics, highlighting system collectivity effects.

Findings

Femtoscopic parameters increase with multiplicity.

Presence of emission asymmetry indicates collectivity.

Source size decreases with increasing pair transverse momentum.

Abstract

The non-identical particle femtoscopy is a technique that is developed to estimate the dimension of a particle-emitting medium as well as the average pair-emission asymmetry between the particles using two-particle correlation functions. The analysis of femtoscopic correlations for all possible charged combinations of pion-kaon pairs in Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV with ALICE at the LHC is presented in this article. The results are extracted for different centrality classes of Pb$-$Pb collisions using the spherical harmonics representations of the correlation functions, $C^{\rm 0}_{\rm 0}$ and $Re C^{\rm 1}_{\rm 1}$. The evolution of the femtoscopic parameters with multiplicity and collectivity of the system is discussed extensively. The femtoscopic parameters are observed to increase with the multiplicity. The non-zero values of pair-emission asymmetry and the decrease of source-size with increasing pair-transverse momentum indicate the presence of collectivity in the system.