Eccentricity fluctuation effects on elliptic flow in relativistic heavy ion collisions

We study effects of eccentricity fluctuations on the elliptic flow coefficient nu(2) at midrapidity in both Au + Au and Cu + Cu collisions at root S-NN = 200 GeV by using a hybrid model that combines ideal hydrodynamics for space-time evolution of the quark gluon plasma phase and a hadronic transport model for the hadronic matter. For initial conditions in hydrodynamic simulations, both the Glauber model and the color glass condensate model are employed to demonstrate the effect of initial eccentricity fluctuations originating from the nucleon position inside a colliding nucleus. The effect of eccentricity fluctuations is modest in semicentral Au + Au collisions, but significantly enhances nu(2) in Cu + Cu collisions.