Two-particle Bose-Einstein correlations and their Lévy parameters in PbPb collisions at Formula Presented TeV

Two-particle Bose-Einstein momentum correlation functions are studied for charged-hadron pairs in lead-lead collisions at a center-of-mass energy per nucleon pair of Formula Presented. The data sample, containing Formula Presented minimum bias events corresponding to an integrated luminosity of 0.607 Formula Presented, was collected by the CMS experiment in 2018. The experimental results are discussed in terms of a Lévy-type source distribution. The parameters of this distribution are extracted as functions of particle pair average transverse mass and collision centrality. These parameters include the Lévy index or shape parameter Formula Presented, the Lévy scale parameter Formula Presented, and the correlation strength parameter Formula Presented. The source shape, characterized by Formula Presented, is found to be neither Cauchy nor Gaussian, implying the need for a full Lévy analysis. Similarly to what was previously found for systems characterized by Gaussian source radii, a hydrodynamical scaling is observed for the Lévy Formula Presented parameter. The Formula Presented parameter is studied in terms of the core-halo model.