  Using the latest data concerning $dN_{\rm ch}/d\eta$ at $\sqrt{s_{NN}} = 200$
GeV, we have analyzed them by means of stochastic theory named the
Ornstein-Uhlenbeck process with two sources. Moreover, we display that $z_r =
\eta/\sqrt{< \eta^2>} = \eta/\eta_{rms}$ scaling with centrality cuts are
described by two Gaussian distributions.
