Publication : t16/072

Abstract:
Using event-by-event hydrodynamic calculations, we find that the fluctuations of the elliptic flow ($v_2$) in the reaction plane have a negative skew. Comparing the skewness of the $v_2$ fluctuations to that of the initial eccentricity fluctuations, we show that skewness is the main effect that separates higher-order cumulants. Furthermore, negative skew corresponds to the hierarchy $v_2{4}>v_2{6}$ observed in Pb+Pb collisions at the LHC. We describe how the skewness can be measured experimentally and show that hydrodynamics naturally reproduces its magnitude and centrality dependence.

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