Parton densities and saturation scale from non-linear evolution in DIS on nuclei

Abstract

We present the numerical solution of the non-linear evolution equation for DIS on nuclei for $x=10^{-2}\tilde{A}\cdot 10^{-7}$. We demonstrate that the solution to the non-linear evolution equation is quite different from the Glauber - Mueller formula which was used as the initial condition for the equation. We illustrate the energy profit for performing DIS experiments on nuclei. However, it turns out that the gain is quite modest: $x_{Au}\simeq 5x_{\mathrm{proton}}$ for the same parton density. We find that the saturation scale $Q_s^2\propto A^{1/3}$. For gold the saturation scale $Q_{s,Au}\simeq 1.5GeV$ at $x=10^{-3}$. Such a large value leads to considerable contribution of the high density QCD phase to RHIC data and reveals itself in essential damping for both $x{G}_A$ and $F_{2A}$.

19 pages, 28 figures