Publication : t17/015

Abstract:
Elliptic flow, v 2 , and triangular flow, v 3 , are to a good approximation linearly proportional to the corresponding spatial anisotropies of the initial density profile, ε 2 and ε 3 . Using event-by-event hydrodynamic simulations, we point out when deviations from this linear scaling are to be expected. When these deviations are negligible, relative v n fluctuations are equal to relative ε n fluctuations, and one can directly probe models of initial conditions using ratios of cumulants, for instance v n {4}/v n {2} . We argue that existing models of initial conditions tend to overestimate flow fluctuations in central Pb+Pb collisions, and to underestimate them in peripheral collisions. We make predictions for v 3 {6} in noncentral Pb+Pb collisions, and for v 3 {4} and v 3 {6} in high-multiplicity p+Pb collisions.

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