Non-Gaussian elliptic-flow fluctuations in PbPb collisions at root S-NN=5.02 TeV
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Abstract
Event-by-event fluctuations in the elliptic-flow coefficient ({v}{2}) are studied in PbPb collisions at (\sqrt{{s}{\text{NN}}}=5.02) TeV using the CMS detector at the CERN LHC. Elliptic-flow probability distributions (p\left({v}{2}\right)) for charged particles with transverse momentum (0.3<{p}{T}<3.0)(\phantom{\rule{0.2em}{0ex}}\text{GeV}/c) and pseudorapidity (|\eta |<1.0) are determined for different collision centrality classes. The moments of the (p\left({v}{2}\right)) distributions are used to calculate the ({v}{2}) coefficients based on cumulant orders 2, 4, 6, and 8. A rank ordering of the higher-order cumulant results and nonzero standardized skewness values obtained for the (p\left({v}_{2}\right)) distributions indicate non-Gaussian initial-state fluctuations. Bessel–Gaussian and elliptic power fits to the flow distributions are studied to characterize the initial-state spatial anisotropy.