Exclusive η c photo-and electroproduction at HERA as a possible probe of the odderon singularity in QCD. Abstract Theory and phenomenology of the η c photo-and electroproduction is developed from the point of view of probing the odderon singularity in QCD which corresponds to the three gluon exchange mechanism. This mechanism leads to the cross-sections which are independent of W 2 for the exch...

We estimate the sizeable cross section for deep exclusive electroproduction of an exotic J = 1 hybrid meson in the Bjorken regime. The production amplitude scales like the one for usual meson electroproduction, i.e. as 1/Q. This is due to the non-vanishing leading twist distribution amplitude for the hybrid meson, which may be normalized thanks to its relation to the energy momentum tensor and ...

Assuming the proton’s light-cone wave function to be dominated by small parton virtualities and small intrinsic transverse momenta, we show that the electroproduction amplitudes at large momentum transfer factorize into parton-level subprocess amplitudes and form factors representing 1/xmoments of skewed parton distributions. On the basis of a wave function overlap model for the form factors we...

Results on elastic vector meson production at HERA are presented in the framework of perturbative QCD. The energy dependence of the cross section for J/ψ photoproduction and for ρ electroproduction is studied. A full polarisation analysis, including the measurement of the 15 elements of the spin density matrix and of R = σL/σT , is presented for ρ electroproduction. Finally heavier vector meson...

A large data set of charged-pion (pi+/-) electroproduction from both hydrogen and deuterium targets has been obtained spanning the low-energy residual-mass region. These data conclusively show the onset of the quark-hadron duality phenomenon, as predicted for high-energy hadron electroproduction. We construct several ratios from these data to exhibit the relation of this phenomenon to the high-...

We estimate the sizeable cross section for deep exclusive electroproduction of an exotic J = 1 hybrid meson in the Bjorken regime. The production amplitude scales like the one for usual meson electroproduction, i.e. as 1/Q. This is due to the non-vanishing leading twist distribution amplitude for the hybrid meson, which may be normalized thanks to its relation to the energy momentum tensor and ...

Exclusive electroproduction of a K or K meson on the nucleon can give a Θ pentaquark in the final state. This reaction offers an opportunity to investigate the structure of pentaquark baryons at parton level. We discuss the generalized parton distributions for the N → Θ transition and give the leading order amplitude for electroproduction in the Bjorken regime. Different production channels con...

The proton, neutron and deuteron structure functions F2(x,Q 2) and g1(x,Q 2), measured at intermediate Q2, are analyzed within a Regge approach. This analysis serves to fix the parameters of this scheme which are then used to calculate, in a unified Regge approach, the properties of ρ0 meson electroproduction on the proton and the deuteron. In this way, the double-spin asymmetry observed at HER...