Collins Effect from Polarized SIDIS and e+e−e^+e^- Data

The recent data on the transverse single spin asymmetry $A_{UT}^{\sin(\phi_h+\phi_S)}$ from HERMES and COMPASS Collaborations are analysed within LO parton model with unintegrated parton distribution and fragmentation functions. A fit of SIDIS data from HERMES Collaboration is performed leading to the extraction of favoured and unfavoured Collins fragmentation functions. A very good description of COMPASS data is obtained. BELLE $e^+e^-$ data are shown to be compatible with our estimates based on the extracted Collins fragmentation functions. Predictions for $A_{UT}^{\sin(\phi_h+\phi_S)}$ asymmetries at JLab and COMPASS operating on a proton target are given.Comment: Talk presented at SPIN2006, 4 pages, 6 figure

The First Three Pomerons

A model of a three Pomeron contribution to high energy elastic $pp$ and $\bar p p$ scattering is proposed. The data are well described for all momenta ($0.01\le |t|\le 14. GeV^2$) and energies ($8.\le\sqrt{s}\le 1800. GeV$) ($\chi^2/{\rm d.o.f.}=2.74$). The model predicts the appearance of two dips in the differential cross-section which will be measured at LHC. The parameters of the Pomeron trajectories are: $\alpha(0)_{{\Bbb P}_1}=1.058, \alpha'(0)_{{\Bbb P}_1}=0.560 (GeV^{-2});$ $\alpha(0)_{{\Bbb P}_2}=1.167, \alpha'(0)_{{\Bbb P}_2}=0.273 (GeV^{-2});$ $\alpha(0)_{{\Bbb P}_3}=1.203, \alpha'(0)_{{\Bbb P}_3}=0.094 (GeV^{-2}).$Comment: 26 pages, 16 figure

Regge-Eikonal Approach and its off-Shell Extention Versus Experimental Data

We develop an off-shell extention of the Regge-eikonal approach which automatically takes into account off-shell unitarity. We argue that exclusive vector-meson production cross-sections measured at HERA can be fairly described with classical universal Regge trajectories. No extra ``hard'' trajectories of high intercept are needed for that.Comment: 15 pages, 18 figures, uses ws-p8-50x6-00.cls, epsf.sty, amsfonts.sty, to be published in the Proceedings of the International Conference on Elastic and Diffractive Scattering (VIIIth 'Blois Workshop') June 28 - July 2, 1999 Protvino, Russi

Partonic Transverse Motion in Unpolarized Semi-Inclusive Deep Inelastic Scattering

We analyse the role of partonic transverse motion in unpolarized Semi-Inclusive Deep Inelastic Scattering (SIDIS) processes. Imposing appropriate kinematical conditions, we find some constraints which fix an upper limit to the range of allowed kt values and lead to interesting results, particularly for some observables like the azimuthal modulation of the unpolarized SIDIS cross section and the average transverse momentum of the final, detected hadron.Comment: To appear in the Proceedings of the XIX International Workshop on Deep-Inelastic Scattering and Related Subjects (DIS 2011), April 11-15, 2011, Newport News, VA US