Higher-order moments of the elliptic flow distribution in PbPb collisions at $$ \sqrt{s_{\textrm{NN}}} $$ = 5.02 TeV
Аннотация
A bstract 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 {2 k }, are measured up to the tenth order ( k = 5) as functions of the collision centrality at a nucleon-nucleon center-of-mass energy of $$ \sqrt{s_{\textrm{NN}}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:msub> <mml:mi>s</mml:mi> <mml:mi>NN</mml:mi> </mml:msub> </mml:msqrt> </mml:math> = 5 . 02 TeV. The data were recorded by the CMS experiment at the LHC and correspond to an integrated luminosity of 0.607 nb − 1 . A hierarchy is observed between the coefficients, with v 2 {2} > v 2 {4} ≳ v 2 {6} ≳ v 2 {8} ≳ 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.
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