Related papers: A model for high energy rho meson leptoproduction …
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…
We consider the exclusive photoproduction of a di-meson pair with large invariant mass, $\gamma N \rightarrow N' M_1M_2$, in the framework of collinear factorisation. The mesons considered $M_1$ and $M_2$ are either pions or rho mesons,…
We calculate in the framework of collinear factorization the amplitude for the photoproduction of a near forward large mass diphoton at leading twist and next to leading order (NLO) in $\alpha_s$. We demonstrate the validity of…
The elastic leptoproduction of $\phi$ measured by the H1 collaboration at HERA is described by a perturbative QCD model, based on open $s\bar{s}$ production and parton hadron duality, proposed by Martin et al. We observe that both the total…
We discuss the production of hadrons in polarized lepton nucleon interactions and in the current jet fragmentation region; using the QCD hard scattering formalism we compute the helicity density matrix of the hadron and show how its…
We consider the electroproduction of two vector mesons with a large rapidity gap between them on a nucleon target in the process $ \gamma ^* N \to \rho_1 \rho_2 N'$. We calculate the Born term for this process within the collinear…
We review our results on a new class of $2 \to 3$ exclusive processes, as a probe of both chiral-even and chiral-odd quark GPDs. We consider the exclusive photoproduction of a photon-meson pair, in the kinematics where the pair has a large…
We analyse spin effects in diffractive vector meson leptoproduction at small $x$ on the basis of the generalized parton distribution (GPD) approach. We take into account quark transverse degrees of freedom in the hard subprocess. We…
Exclusive photoproduction of a $\gamma\,\rho$ pair in the kinematics where the pair has a large invariant mass and the final nucleon has a small transverse momentum is described in the collinear factorization framework. The scattering…
We present recent experimental data from the H1 and ZEUS Collaborations at HERA for diffractive dijet production in deep-inelastic scattering (DIS) and photoproduction and compare them with next-to-leading order (NLO) QCD predictions using…
We present here some arguments to support our suggestion that data on the helicity structure for the hard exclusive electroproduction of $\rho$ mesons at HERA (and in possible future high-energy electron-proton colliders) provide useful…
We develop a dipole model for HERA DIS data which incorporates the impact parameter distribution of the proton. The model describes the inclusive total $\gamma^*p$ cross-sections as well as the diffractive $J/\psi$ differential…
Results from a phenomenological analysis of $W$ and $Z$ hard diffractive hadroproduction at high energies are reported. Using the Regge factorization approach, we consider the recent diffractive parton density functions extracted by the H1…
Exclusive rho^0-meson electroproduction is studied in the HERMES experiment, using a 27.6 GeV longitudinally polarized electron/positron beam and unpolarized hydrogen and deuterium targets in the kinematic region 0.5 GeV^2 < Q^2 < 7.0…
Results for semi-leptonic form-factors for processes like $D \to K l \nu$ and the Bethe-Salpeter amplitudes (BSA) for pion and rho mesons are presented. The form-factor data is consistent with previous calculations. We find that the long…
O(\alpha) QED radiative corrections to polarized neutral current leptoproduction of heavy quark flavours are calculated in the leading log approximation for HERMES, COMPASS, and HERA kinematics. Besides the inclusive case, we derive general…
We study diffractive hard dijet production, with one or two rapidity gaps, at high energies. We emphasize that both hard and Regge factorization are broken in these processes. We show that a multi-Pomeron-exchange model for screening…
We investigate $\rho$ vector meson production in $ep$ collisions at HERA with leading neutrons in the dipole formalism. The interaction of the dipole and the pion is described in a mixed-space approach, in which the dipole-pion scattering…
We demonstrate that the distinctive features of the forward differential cross section of diffractive leptoproduction of a vector meson can be legitimately calculated in perturbative QCD in terms of the light-cone $q \bar q$ wave function…
In standard Regge theory with a pomeron intercept a(0)=1+\epsilon, the contribution of the tripe-pomeron amplitude to the t=0 differential cross section for single diffraction dissociation has the form d\sigma/dM^2(t=0) \sim…