QCD Saturation and Soft Processes

We show that an approximate solution to the amended non-linear Balitsky-Kovchegov evolution equation which was formulated for hard QCD processes, can be extended to provide a good description of photoproduction and soft hadronic (non perturbative) reactions.Comment: 3 pages, 4 Postscript figures, Contribution to the Proceedings of the International European Conference on High Energy Physics EPS (July 17-23, 2003) Aachen, German

Survival probability of large rapidity gaps in QCD and N=4 SYM motivated model

In this paper we present a self consistent theoretical approach for the calculation of the Survival Probability for central dijet production . These calculations are performed in a model of high energy soft interactions based on two ingredients:(i) the results of N=4 SYM, which at the moment is the only theory that is able to deal with a large coupling constant; and (ii) the required matching with high energy QCD. Assuming, in accordance with these prerequisites, that soft Pomeron intercept is rather large and the slope of the Pomeron trajectory is equal to zero, we derive analytical formulae that sum both enhanced and semi-enhanced diagrams for elastic and diffractive amplitudes. Using parameters obtained from a fit to the available experimental data, we calculate the Survival Probability for central dijet production at energies accessible at the LHC. The results presented here which include the contribution of semi-enhanced and net diagrams, are considerably larger than our previous estimates.Comment: 11 pages, 10 pictures in .eps file

Behaviour of the forward peak in hard diffractive leptoproduction of vector mesons

The measured forward slope in elastic and inelastic leptoproduction of vector mesons differ by a substantial amount. In an attempt to describe this phenomenon we construct a two radii model for the target proton, and estimate the effective parameters of the hard Pomeron obtained from a pQCD dipole model with eikonal shadowing corrections (SC). We show that the SC reduce the intercept of the hard Pomeron and generate an effective shrinkage of the forward peak and a diffractive dip at $|t| \approx 1 GeV^2$, which appears to affect the value of the experimentally measured slope.Comment: 18 pages, 7 figures, one table, everything in tar.gz fil

A model for strong interactions at high energy based on the CGC/saturation approach

We present our first attempt to develop a model for soft interactions at high energy, based on the BFKL Pomeron and the CGC/saturation approach. We construct an eikonal-type model, whose opacity is determined by the exchange of the dressed BFKL Pomeron. The Green's function of the Pomeron is calculated in the framework of the CGC/saturation approach. Using five parameters we achieve a good description of the experimental data at high energies ( $W\,\geq\,0.546\,TeV$). The model results in different behaviour for the single and double diffraction cross sections at high energies. The single diffraction cross section reaches a saturated value (about 10 mb) at high energies, while the double diffraction cross section continues growing slowlyComment: 21 pp. 16 figures in eps file