Scaling phenomena from non-linear evolution in high energy DIS

The numerical solutions of the non-linear evolution equation are shown to display the ``geometric'' scaling recently discovered in the experimental data. The phenomena hold both for proton and nucleus targets for all $x$ below $10^{-2}$ and $0.25 {\rm GeV^{2}}\le Q^2 \le 2.5\times10^3 {\rm GeV^{2}}$. The scaling is practically exact (few percent error) in the saturation region. In addition, an approximate scaling is found in the validity domain of the linear evolution where it holds with about 10% accuracy. Basing on the scaling phenomena we determine the saturation scale $Q_s(x)$ and study both its $x$-dependence and the atomic number dependence for the nuclei.Comment: 13 pages, 20 figure

Diffractive dissociation and saturation scale from non-linear evolution in high energy DIS

This paper presents the first numerical solution to the non-linear evolution equation for diffractive dissociation processes in deep inelastic scattering. It is shown that the solution depends on one scaling variable $\tau = Q^2/Q^{D 2}_s(x,x_0)$, where $Q^D_s(x,x_0)$ is the saturation scale for the diffraction processes. The dependence of the saturation scale $Q^D_s(x,x_0)$ on both $x$ and $x_0$ is investigated, ($Y_0 = \ln(1/x_0)$ is a minimal rapidity gap for the diffraction process). The $x$ - dependence of $Q^D_s$ turns out to be the same as of the saturation scale in the total inclusive DIS cross section. In our calculations $Q^D_s(x,x_0)$ reveals only mild dependence on $x_0$. The scaling is shown to hold for $x \ll x_0$ but is violated at $x \sim x_0$.Comment: 13 pages, 9 figure

Towards a new global QCD analysis: low x DIS data from non-linear evolution

A new approach to global QCD analysis is developed. The main ingredients are two QCD-based evolution equations. The first one is the Balitsky-Kovchegov nonlinear equation, which sums higher twists while preserving unitarity. The second equation is linear and it is responsible for the correct short distance behavior of the theory, namely it includes the DGLAP kernel. Our approach allows extrapolation of the parton distributions to very high energies available at the LHC as well as very low photon virtualities, $Q^2\ll 1 {\rm GeV^2}$. All existing low $x$ data on the $F_2$ structure function is reproduced using one fitting parameter. The resulting $\chi^2/df=1$. Analyzing the parameter $\lambda\equiv \partial\ln F_2/\partial(\ln 1/x)$ at very low $x$ and $Q^2$ well below $1 {\rm GeV^2}$ we find $\lambda \simeq 0.08 - 0.1$. A result which agrees with the "soft pomeron" intercept without involving soft physics.Comment: 27 pages, 11 figure

High-enegy effective action from scattering of QCD shock waves

At high energies, the relevant degrees of freedom are Wilson lines - infinite gauge links ordered along straight lines collinear to the velocities of colliding particles. The effective action for these Wilson lines is determined by the scattering of QCD shock waves. I develop the symmetric expansion of the effective action in powers of strength of one of the shock waves and calculate the leading term of the series. The corresponding first-order effective action, symmetric with respect to projectile and target, includes both up and down fan diagrams and pomeron loops.Comment: 15 pages, 10 eps figure

Non-linear evolution and high energy diffractive production

The ratio of the diffractive production to the total cross section in DIS is computed as a function of the produced mass. The analysis is based on the solution to the non-linear evolution equation for the diffraction dissociation in DIS. The obtained ratios almost do not depend on the central mass energy in agreement with the HERA experimental data. This independence is argued to be a consequence of the scaling phenomena displayed by the cross sections. As a weakness point a significant discrepancy between the data and the obtained results is found in the absolute values of the ratios. Several explanatory reasons are discussed.Comment: 8 pages, 3 figure