Diffractive hadron leptoproduction and SPD

We discuss diffractive hadron leptoproduction in terms of skewed gluon distributions and within two-gluon exchange model. Connection of the two-gluon approach with skewed gluon distributions is found. The double spin asymmetries for longitudinally polarized leptons and transversely polarized protons in diffractive vector meson and $Q \bar Q$ production at high energies within the two-gluon model is analysed. The asymmetry predicted for meson production is found to be quite small. The $A_{lT}$ asymmetry for $Q \bar Q$ production is large and can be used to obtain information on the polarized skewed gluon distributions in the proton.Comment: 16 pages, latex, 9 figures, lectures presented at the Conference "Symmetries and Spin" - Praha-SPIN-2002, Prague, July 14 - 27, 200

GPDs and spin effects in light mesons production

Light meson electroproduction is analyzed on the basis of the handbag approach. Our results on the cross section and spin effects are in good agrement with experiments at HERA, COMPASS and HERMES energies. Predictions for $A_{UT}$ asymmetry for various reactions are presented.Comment: 8 pages, 14 figs, report at the Advanced Studies Institute Symmetries And Spin (SPIN-Praha-2009) Prague, July 26 - August 2, 200

Polarized GPDs in pions and kaons electroproduction. Tranversity effects

We analyze the electroproduction of pseudoscalar mesons within the handbag approach. To investigate these reactions, we consider the leading-twist contribution together with the transversity twist-3 effects that are crucial in the description of experimental data. Our results on the cross section are in agreement with experiment. We present our predictions for spin observables.Comment: 8 pages, 12 figures, talk at the International Conference "Advanced Studies Institute Symmetries And Spin" (SPIN-Praha-2012) Prague, July 1 - 8, 201

Spin Effects and Amplitude Structure in Vector Meson Photoproduction at Small xx

An analysis of light vector meson photoproduction at small $x$ on the basis of the generalized parton distribution (GPD) approach is presented. Our results on the cross section and spin density matrix elements (SDME) are in fair agreement with DESY experiments. The predicted double spin longitudinal $A_{LL}$ asymmetry is not small at HERMES energies.Comment: LateX file (use wrapfile.sty), 4 figures, report at the XI Workshop on High Energy Spin Physics, Dubna, Russia, September 27 - October 1, 200

Spin Asymmetries In Proton-Proton Scattering At High Energies And Moderately Large Momentum Transfer

We study $pp$ scattering at high energies and moderately large momentum transfer using a QCD--based model in which the proton is viewed as being composed of a quark and a diquark. This model leads to spin asymmetries which are neither small nor vanish at high energies. The predicted ratio of helicity flip and non-flip amplitudes is about 0.2-0.3 and $A_n$ asymmetry is about 20-30% for $|t| > 4 {GeV}^2$.Comment: Latex, 3 pages, 2 figures, uses sprocl.sty. Talk at SPIN98 symposium, September 8-12, Protvino, Russi

Large - Distance Effects in QCD and Spin Asymmetries in Diffractive Reactions

Large - distance effects in the hadron wave function for the hadron-Pomeron vertex in the QCD -model are discussed. It is shown that they lead to the spin-flip part of the Pomeron coupling which can reach $10 \div 20$ with respect to the non-flip part. The obtained structure of the Pomeron coupling modifies spin asymmetries in high--energy diffractive reactions where the Pomeron structure becomes determinative. We study spin asymmetries in exclusive reactions and in the diffractive $Q \bar Q$ and $J/\Psi$ production. We have found that spin effects in these diffractive processes are sensitive to the spin-flip part of the Pomeron coupling.Comment: Report at the XIV International Seminar On High Energy Physics Problems "RELATIVISTIC NUCLEAR PHYSICS AND QUANTUM CHROMODYNAMICS" Dubna, August 17-22, 199

Double spin asymmetry in diffractive QQˉQ \bar Q production at SMC energies and quark-pomeron vertex structure

It is shown that the longitudinal double spin asymmetry $A_{ll}$ in polarized diffractive $l p \to l p+Q \bar Q$ reaction depends strongly on the spin structure of quark-pomeron vertex. The SMC spin facilities may be one of the best place to perform such experiment.Comment: 5 pages, Latex, 3 figures are appended at the end (as uufile

Spin asymmetries in diffractive high-energy reactions

The analysis of some effects caused by the spin--dependent pomeron couplings is presented. It is shown that the structure of pomeron--proton and quark--pomeron couplings can be tested in future polarized experiments on elastic $pp$ reactions and diffractive $Q \bar Q$ production.Comment: 9 pages with 6 figures, LaTex, Talk presented at the Adriatico Research Conference "Trends in Collider Spin Physics" (5 - 8 December 1995) ICTP, Miramare Trieste, Ital

Effects of Quark-Pomeron Coupling Structure in Diffractive Deep Inelastic Scattering

We study the contribution of diffractive $Q \bar Q$ production to the $F_2^D$ proton structure function and the longitudinal double-spin asymmetry in polarized deep--inelastic $lp$ scattering. We show the strong dependence of the $F_2^D$ structure function and the $A_{ll}$ asymmetry on the quark--pomeron coupling structure.Comment: 15 pages, latex, 5-Ps figure

Diffractive hadron production and pomeron coupling structure

Large-distance effects, which lead to the spin-flip part of the hadron -pomeron coupling in QCD -models, are discussed. We study spin asymmetries in exclusive reactions and in diffractive $Q \bar Q$ and vector meson production which are sensitive to the spin-dependent part of the pomeron coupling.Comment: 6 pages, latex, 4 figures, to be published in Proc. of the International Bogolyubov Conference "Problems of Theoretical and Mathematical Physics", September 27- October 6, Moscow-Dubna-Kyi