Related papers: Unitarity constraints on meson electroproduction a…
Results on elastic electroproduction of rho mesons are presented for a photon virtuality in the range 1 < Q^2 < 60 GeV^2 and for a hadronic centre of mass energy in the range 30 < W < 140 GeV. The shape of the (pi pi) mass distribution is…
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…
The differential cross section, $d\sigma/dt$ for $\omega$ meson exclusive photoproduction on the proton above the resonance region ($2.6<W<2.9$ GeV) was measured up to a momentum transfer $-t = 5$ GeV$^2$ using the CLAS detector at…
One-loop corrections due to the intermediate $\pi N$ and $\rho N$ states are studied in $\omega$ photoproduction near threshold. Our results show that the coupled-channel effects should be taken into account in extracting reliable nucleon…
We present a quark model study of the $\omega$ meson photoproduction near threshold. With a limited number of parameters, all the data in history are reproduced. The roles played by the {\it s}- and {\it u}-channel processes (resonance…
The differential cross section, $d\sigma/dt$, for $\rho^0$ meson photoproduction on the proton above the resonance region ($2.6<W<2.9$ GeV) was measured up to a momentum transfer $-t = 5$ GeV$^2$ using the CLAS detector at the Thomas…
Exclusive production of $\omega$ mesons was studied at the COMPASS experiment by scattering $160~\mathrm{GeV}/\mathit{c}$ muons off transversely polarised protons. Five single-spin and three double-spin azimuthal asymmetries were measured…
We consider photoproduction of $\omega$ mesons off complex nuclei to study interactions of transversely and longitudinally polarized vector mesons with nucleons. Whereas the total cross section for interactions of the transversely polarized…
We have investigated exclusive photoproduction of light vector mesons ($\omega$, $\rho$ and $\phi$) on the nucleon at low energies. In order to explore the questions concerning the so-called missing nucleon resonances, we first establish…
Exclusive $\pi^o$ electroproduction and related processes are suggested to investigate the chiral odd transversity distributions of quarks in the transversely polarized nucleon, $h_1(x)$, and its first moment, the tensor charge. The…
The exclusive production of pairs of vector mesons with J^{PC} = 1^{--} in e^+ e^- collisions can proceed through e^+ e^- annihilation into two virtual photons. At energies much greater than the meson masses, the cross section is dominated…
Exclusive electroproduction of $\omega$ mesons on unpolarized hydrogen and deuterium targets is studied in the kinematic region of Q$^2$>1.0 GeV$^2$, 3.0 GeV < W < 6.3 GeV, and -t'< 0.2 GeV$^2$. Results on the angular distribution of the…
We study universality in the electroproduction of vector mesons using a unified nonperturbative approach which has already proved to reproduce extremely well the available experimental data. In this framework, after the extraction of…
Background: Measurements of forward exclusive meson production at different squared four-momenta of the exchanged virtual photon, $Q^2$, and at different four-momentum transfer, t, can be used to probe QCD's transition from meson-nucleon…
In these proceedings we present preliminary $\pi^{+}\pi^{-}$ electroproduction cross sections off protons in the kinematical area of 1.4 GeV $< W <$ 1.8 GeV and 0.4 GeV$^{2}$ $< Q^{2} < 1.1$ GeV$^{2}$. Our results extend the kinematical…
We provide an analysis of vector meson photoproduction in the channel of the vector meson decaying into a pseudoscalar meson plus a photon, i.e. $V\to P\gamma$. It is shown that non-trivial kinematic correlations arise from the measurement…
We consider two coupled problems. We study the dependence on photon virtuality $Q^2$ for the semihard quasi--elastic photoproduction of neutral vector mesons on a quark, gluon or real photon (at $s\gg p_{\bot}^2,\;Q^2; \; p_{\bot}^2\gg…
The differential cross sections and unpolarized spin-density matrix elements for the reaction $\gamma p\to p\omega$ were measured using the CBELSA/TAPS experiment for initial photon energies ranging from the reaction threshold to 2.5 GeV.…
We consider backward vector meson exclusive electroproduction off nucleons in the framework of collinear QCD factorization. Nucleon to vector meson transition distribution amplitudes arise as building blocks for the corresponding factorized…
Exclusive diffractive production of real photons and vector mesons in ep collisions has been studied at HERA in a wide kinematic range. Here we present and discuss a Regge-type model of real photon production (Deeply Virtual Compton…