http://alzt.tau.ac.il/~halina/papha/pap4.pdf

Measurement of the proton structure function F2 in ep scattering at HERA

Structure functions and low x physics

Hard diffractive electroproduction of longitudinally polarized vector mesons is calculated within the leading {alpha}{sub {ital s}}ln({ital Q}{sup 2}/{Lambda}{sub QCD}{sup 2}) approximation of QCD using the leading order parton densities within the nucleon. Novel QCD features of the production of excited states and of the restoration of flavor symmetry are analyzed. At the onset of the asymptotic regime, our analysis finds an important role of quark Fermi motion within the diffractively produced vector mesons, and we suggest to use this effect to measure the high momentum tail of the wave function of the vector mesons. We deduce a kinematical boundary for the region of applicability of the decomposition of the hard amplitudes over powers of {ital Q}{sup 2} and/or a limit on the increase of the cross sections of hard processes at small {ital x}, and briefly analyze its consequences. We also estimate the nuclear attenuation of the diffractive electroproduction of vector mesons and compare with estimates of the shadowing of the longitudinal structure function. {copyright} {ital 1996 The American Physical Society.}

Hard diffractive electroproduction of vector mesons in QCD.

We develop the novel description of diffractive deep inelastic scattering based on the technique of lightcone wave functions of multiparton Fock states of the photon. The technique takes advantage of the exact diagonalization of the diffractiveS-matrix in the dipole-cross section representation. In this paper we derive properties of the diffractive dissociation of virtual photons in the triple-pomeron regime. We demonstrate that the photonpomeron interactions can be described by the partonic structure function, which satisfies the conventional GLDAP evolution equations. We identify the valence and sea (anti) quark and the valence gluon structure functions of the pomeron. We show how the gluon structure of the pomeron can be described by the constituent gluon wave function. We derive the leading unitarization correction to the rising structure functions at smallx and conclude that the unitarized structure function satisfies the linear GLDAP evolution equations. This result holds even when the multipomeron exchanges are included.

The Triple pomeron regime and the structure function of the pomeron in the diffractive deep inelastic scattering at very small x

Pion structure function in the Nambu and Jona-Lasinio model

This article reviews the physics of deep-inelastic lepton-hadron processes in the region of small {ital x}, where {ital x} is the Bjorken scaling variable. The theoretical concepts concerning the Regge limit of deep-inelastic scattering are summarized and recent theoretical results on the small-{ital x} limit of parton distributions in perturbative QCD are discussed. Presently available experimental data on the free- and bound-nucleon structure functions at small {ital x} are reviewed in detail and their theoretical interpretations (including the low-{ital x}, low-{ital Q}{sup 2} region) are discussed. QCD predictions are given for the deep-inelastic scattering structure functions {ital F}{sub 2} and {ital F}{sub {ital L}} in the small-{ital x} (10{sup {minus}5}{lt}{ital x}{lt}10{sup {minus}2}) and moderately large-{ital Q}{sup 2} region relevant for HERA ({ital Q}{sup 2}{similar to}10 GeV{sup 2}).

B. Badelek

Papers

Small- x physics in deep-inelastic lepton-hadron scattering