Importance of correlations and fluctuations on the initial source eccentricity from Glauber simulations

Abstract

Various ways of defining the initial source eccentricity in nucleus-nucleus collisions are discussed. In particular, we examine the participant eccentricity, which quantifies the eccentricity of the initial source shape by the major axes of the overlap ellipse formed by the interaction points of the participating nucleons. We find that participant spatial correlations in the interaction of two nuclei play an essential role, in particular for the Cu+Cu system. Including these correlations in the calculation of the participant eccentricity results in larger values for the eccentricity.