Nonlinear evolution and saturation for heavy nuclei in DIS

The nonlinear evolution equation for the scattering amplitude of colour dipole off the heavy nucleus is solved in the double logarithmic approximation. It is found that if the initial parton density in a nucleus is smaller then some critical value, then the scattering amplitude is a function of one scaling variable inside the saturation region, whereas if it is greater then the critical value, then the scaling behaviour breaks down. Dependence of the saturation scale on the number of nucleons is discussed as well.Comment: 12 pages, 1 figur

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

We present the numerical solution of the non-linear evolution equation for DIS on nuclei for $x = 10^{-2} \div 10^{-7}$. 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: $x_{Au} \simeq 5 x_{\rm proton}$ for the same parton density. We find that the saturation scale $Q^2_s \propto A^{{1/3}}$. For gold the saturation scale $Q_{s,Au} \simeq 1.5 GeV$ 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 $xG_A$ and $F_{2A}$.Comment: 19 pages, 28 figure

QCD motivated approach to soft interactions at high energies: nucleus-nucleus and hadron-nucleus collisions

In this paper we consider nucleus-nucleus and hadron-nucleus reactions in the kinematic region: g A^{1/3} G_{3\pom} \exp\Lb \Delta Y\Rb \approx 1 G^2_{3\pom} \exp\Lb \Delta Y\Rb \approx 1 , where G_{3\pom} is the triple Pomeron coupling, $g$ is the vertex of Pomeron nucleon interaction, and 1 + \Delta_{\pom} denotes the Pomeron intercept. We find that in this kinematic region the traditional Glauber-Gribov eikonal approach is inadequate. We show that it is necesssary to take into account inelastic Glauber corrections, which can not be expressed in terms of the nucleon-nucleon scattering amplitudes. In the wide range of energies where \alpha'_\pom Y \ll R^2_A,the scattering amplitude for the nucleus-nucleus interaction, does not depend on the details of the nucleon-nucleon interaction at high energy. In the formalism we present, the only (correlated) parameters that are required to describe the data are \Delta_{\pom}, G_{3\pom} and $g$. These parameters were taken from our description of the nucleon-nucleon data at high energies \cite{GLMM}.The predicted nucleus modification factor is compared with RHIC Au-Au data at $W = 200 GeV.$ Estimates for LHC energies are presented and discusssed.Comment: 18pp. 14 fugure