Related papers: Polarization in diffractive electroproduction of l…
The electroproduction of rho mesons is studied at HERA with the H1 detector at high Q^2 and high |t|. Cross sections are measured as a function of Q^2, W and t. The W dependence of the gamma*-p cross section is observed to increase with Q^2…
In this work the production of vector mesons in diffractive DIS is analyzed, with an emphasis on the impact of the internal spin structure of a vector meson upon its virtual photoproduction rate. We derived the full sets of s-channel…
In this work, we will evaluate the nucleon helicity flip form factor at the limit of large momentum transfer. Hereby, we will study the exchange of one and two virtual photons separately. For the calculation of the scattering amplitudes and…
We estimate the differential and total cross sections for both the photoproduction of vector D*-meson and its yield in deep inelastic scattering at the HERA collider in the framework of model motivated by perturbative calculations in QCD.…
Spin and transverse momentum dependent parton distributions - Generalized Parton Distributions (GPDs) - are at the interface between the QCD structure of the hadrons and observable quantities. The GPDs are linear superpositions within…
We study spin asymmetries in diffractive $Q \bar Q$ and vector meson production which are sensitive to the spin-dependent part of the two-gluon-nucleon coupling. It is found that the $A_{ll}$ and $A_{lT}$ asymmetry in diffractive reactions…
We discuss diffractive photon-production of vector mesons in holographic QCD. At large $\sqrt{s}$, the QCD scattering amplitudes are reduced to the scattering of pair of dipoles exchanging a closed string or a pomeron. We use the…
Multiple polarization observables must be measured to access the amplitude structure of pseudoscalar meson photoproduction off the proton. The hyperon-producing reactions are especially attractive to study, since the weak decays allow…
The process of a light neutral vector meson electroproduction is studied in the framework of QCD factorization in which the amplitude factorizes in a convolution of the nonperturbative meson distribution amplitude and the generalized parton…
We study the spin-dependent cross-sections of vector meson photoproduction for longitudinally and transversely polarized photons within a QCD- model. The dependence of the $\sigma_T/\sigma_L$ ratio on the photon virtuality and on the meson…
The amplitude of diffractive $\rho$ (and open quark) leptoproduction on a polarized target is calculated in the leading log approximation of pQCD using the hadron-parton duality hypothesis. The spin-spin asymmetry is expressed in terms of…
Hard diffractive photo- and electroproduction of heavy vector mesons ($J/\psi$ and $\Upsilon$) is evaluated within the leading $\alpha_s\ln{Q^2 \over\Lambda_{QCD}^2}$ approximation of QCD. In difference from our earlier work on that…
Spin observables may reveal much deeper properties of non perturbative hadronic physics than unpolarized quantities. We discuss the polarization of hadrons produced in $e^+e^-$ annihilation at LEP. We show how final state $q \bar q$…
We discuss the production of polarized hadrons in polarized lepton nucleon interactions and show that the helicity density matrix of the hadron, when measurable, can give information on the spin structure of the nucleon and the spin…
We calculate the differential cross section $d\sigma/dt$ for the diffractive photoproduction process $\gamma p \to \rho p$ and compare to recent data extracted by the CMS collaboration from ultraperipheral proton-lead collisions. Our model…
We have shown that the lowest order QCD amplitude, i.e. the quark exchange contribution, to the forward production of a pair of longitudinally polarized rmesons in the scattering of two virtual photons gamma (Q1) gamma (Q2) rho rho…
We examine diffractive proton-proton scattering p p -> p X and photo- and electroproduction of \rho^0 mesons \gamma^(*) p -> \rho^0 X, where X denotes a proton or a final state, into which the proton can go by diffractive dissociation.…
A review is presented of diffractive vector meson production at HERA, with stress on the investigation of ``hard'' features and comparisons with theoretical predictions based on perturbative QCD approaches.
Plans are underway to measure spin asymmetries at large momentum transfer in hadron hadron collisions at RHIC and elsewhere. Proposals have focused on measuring quark transversity and quark and gluon helicity distributions in the nucleon.…
Electroproduction of two vector mesons with a large rapidity gap between them provides the first feasible selective access to chiral-odd GPDs. The scattering amplitude of the process $ \gamma ^* N \to \rho_L^0 \rho_T^+ N'$ may be…