Higher-order moments of the elliptic flow distribution in PbPb collisions at $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV

The hydrodynamic flow-like behavior of charged hadrons in high-energy lead-lead collisions is studied through multiparticle correlations. The elliptic anisotropy values based on different orders of multiparticle cumulants, $v_{2}\{2k\}$, are measured up to the tenth order ($k = 5$) as functions of the collision centrality at a nucleon-nucleon center-of-mass energy of $\sqrt{s_{\rm{NN}}}=5.02~\textrm{Te}\textrm{V}$. The data were recorded by the CMS experiment at the LHC and correspond to an integrated luminosity of $0.607~\textrm{nb}^{-1}$. A hierarchy is observed between the coefficients, with $v_{2}\{2\} > v_{2}\{4\} \gtrsim v_{2}\{6\} \gtrsim v_{2}\{8\} \gtrsim v_{2}\{10\}$. Based on these results, centrality-dependent moments for the fluctuation-driven event-by-event $v_{2}$ distribution are determined, including the skewness, kurtosis and, for the first time, superskewness. Assuming a hydrodynamic expansion of the produced medium, these moments directly probe the initial-state geometry in high-energy nucleus-nucleus collisions.