Related papers: Spin Density Matrix Elements from diffractive $\ph…
An analysis of light vector meson photoproduction at small $x$ on the basis of the generalized parton distribution (GPD) approach is presented. Our results on the cross section and spin density matrix elements (SDME) are in fair agreement…
As part of a measurement of the cross section of $\phi$ meson photoproduction to high momentum transfer, we measured the polar angular decay distribution of the outgoing $K^+$ in the channel $\phi \to K^+K^-$ in the $\phi$ center-of-mass…
For coherent photoproduction of phi and omega mesons from deuteron at forward angles, the isovector pi-exchange amplitude is strongly suppressed. We show a possibility to study the non-diffractive channels associated with the unnatural…
The cross section and decay angular distributions for the coherent \phi meson photoproduction on the deuteron have been measured for the first time up to a squared four-momentum transfer t =(p_{\gamma}-p_{\phi})^2 =-2 GeV^2/c^2, using the…
We discuss coherent and incoherent $\phi$ meson photoproduction off the deuteron at low energy and small momentum transfer with the aim to check whether the recent experimental data need for their interpretation the inclusion of exotic…
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…
The amplitude ratios of vector-meson production by heavy photons on spinless targets are shown to can be explicitly expressed in terms of the spin-density-matrix elements (SDMEs) only if the lepton beam is longitudinally polarized. Making…
Hard exclusive electroproduction of $\pi^+\pi^-$ pairs off hydrogen and deuterium targets has been studied by the HERMES experiment at DESY. Legendre moments $<P_1>$ and $<P_3>$ of the angular distributions of $\pi^+$ mesons in the…
We discuss results on the diffractive production of the vector mesons rho, phi and omega reported by the H1 and ZEUS collaborations at HERA. Unique to such studies is the experimental accessibility to the polarization of the vector mesons…
New results for the transverse target spin azimuthal asymmetry A_{UT}^{sin(\phi-\phi_S)} for hard exclusive \rho^0-meson production on a transversely polarised ^6LiD and NH_3 target will be presented. The measurement was performed with the…
The diffractive photoproduction of rho mesons, e p \to e rho Y, with large momentum transfer squared at the proton vertex, |t|, is studied with the H1 detector at HERA using an integrated luminosity of 20.1 pb^{-1}. The photon-proton centre…
HERMES is a second generation experiment to study the spin structure of the nucleon, in which measurements of the spin dependent properties of semi-inclusive deep-inelastic lepton scattering are emphasized. Data have been accumulated for…
Production of exclusive dijets in diffractive deep inelastic $e^\pm p$ scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 372 pb$^{-1}$. The measurement was performed for $\gamma^*-p$…
The helicity distribution of the strange quark sea in the proton has been extracted from measurements of polarized production of charged kaons in deep-inelastic scattering from a polarized deuterium target.
Preliminary measurements are reported on the azimuthal single-spin asymmetry of exclusive rho0 mesons for a transversely polarized hydrogen target at HERMES using the 27.6 GeV HERA positron beam. Within the generalized parton distribution…
The PHENIX experiment at the Relativistic Heavy Ion Collider has measured the differential cross section of $\phi$(1020)-meson production at forward rapidity in $p$$+$$p$ collisions at $\sqrt{s}=$510 GeV via the dimuon decay channel. The…
Production of $\phi$ mesons is considered in the course of heavy-ion collisions at SPS energies. We investigate the possible difference in momentum distributions of $\phi$ mesons measured via their leptonic ($\mu^+\mu^-$) and hadronic…
Beam-target double spin asymmetries and target single-spin asymmetries in exclusive $\pi^+$ and $\pi^-$ electroproduction were obtained from scattering of 1.6 to 5.7 GeV longitudinally polarized electrons from longitudinally polarized…
We develop a general framework for studying the spin alignment $\rho_{00}$ for flavorless vector mesons by using the gauge/gravity duality. Focusing on the dilepton production through vector meson decay, we derive the relation between…
We report on the measurement of spin density matrix elements of the $\Lambda(1520)$ in the photoproduction reaction $\gamma p\rightarrow \Lambda(1520)K^+$, via its subsequent decay to $K^{-}p$. The measurement was performed as part of the…