Eccentricity fluctuations and elliptic flow at RHIC

Rajeev S. Bhalerao, Jean-Yves Ollitrault

Published 2006-07-07, updated 2006-08-17Version 2

Fluctuations in nucleon positions can affect the spatial eccentricity of the overlap zone in nucleus-nucleus collisions. We show that elliptic flow should be scaled by different eccentricities depending on which method is used for the flow analysis. These eccentricities are estimated semi-analytically. When $v_2$ is analyzed from 4-particle cumulants, or using the event plane from directed flow in a zero-degree calorimeter, the result is shown to be insensitive to eccentricity fluctuations.