Beam-energy and system-size dependence of dynamical net charge fluctuations

Abstract

We present measurements of net charge fluctuations in Au + Au collisions at s NN = 19.6, 62.4, 130, and 200 GeV, Cu + Cu collisions at s NN = 62.4 and 200 GeV, and p + p collisions at s = 200 GeV using the dynamical net charge fluctuations measure +-,dyn . We observe that the dynamical fluctuations are nonzero at all energies and exhibit a modest dependence on beam energy. A weak system size dependence is also observed. We examine the collision centrality dependence of the net charge fluctuations and find that dynamical net charge fluctuations violate 1/N ch scaling but display approximate 1/N part scaling. We also study the azimuthal and rapidity dependence of the net charge correlation strength and observe strong dependence on the azimuthal angular range and pseudorapidity