Related papers: Hard Meson Electroproduction And Twist-3 Effects
Dielectrons probe a wide range of phenomena in heavy-ion collisions. These include light- and heavy-flavour meson production, thermal radiation and coherent photo-production. The latter process is distinguished by dielectron production at…
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…
We compute the contribution from the twist-3 fragmentation function for light hadron production in collisions between transversely and longitudinally polarized protons, i.e., $p^\uparrow \vec{p} \to h\,X$, which can cause a double-spin…
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/Psi photoproduction and for rho electroproduction is studied. A full polarisation…
We analyze electroproduction of light vector meson at small Bjorken $x$ within the generalized parton distribution (GPD) approach. Calculation is based on the modified perturbative approach, where the quark transverse degrees of freedom in…
We study the pair-production of heavy mesons in proton-antiproton annihilations within a perturbative QCD-motivated framework. In particular we investigate $p \bar{p} \rightarrow \overline{D^0} D^0$ within a double handbag approach, where a…
We evaluate perturbative next-to-leading order corrections to the hard exclusive leptoproduction of pi+ mesons on a transversely polarized proton target. A model dependent study shows that these corrections can be large. We analyze the…
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…
Selected recent results from the H1 and ZEUS experiments are reviewed, illustrating some of the many facets of ``meson physics'' at the HERA ep collider. The results cover exclusive elastic and proton-dissociative diffractive vector meson…
Generalized Parton Distributions (GPDs) provide a dynamical picture of the nucleon. The exclusive production of $\rho^0$ mesons on a transversely polarised target is sensitive to the nucleon helicity-flip GPDs $E$ which are related to the…
We investigate the electroproduction of eta mesons below a center of momentum energy of 1.6 GeV, with particular emphasis on the roles of the N*(1535) and N*(1520) resonances. Using the effective Lagrangian approach, we show that the…
We study the single transverse-spin asymmetry for inclusive light-hadron productions in the proton-proton collision, $\pphx$ ($h=\pi,K,\eta$), for the RHIC kinematics based on the twist-3 mechanism in the collinear factorization. The…
We discuss the electroproduction of pseudoscalar ($0^{-+}$) or scalar ($0^{++}$) meson production off the scalar target. The most general formulation of the differential cross section for the $0^{-+}$ or $0^{++}$ meson production process…
A nonperturbative calculation of elastic electroproduction of the J/psi meson is presented and compared to the experimental data. Our model describes well the observed dependences of the cross sections on the photon virtuality Q2 and on the…
Exclusive pi0 electroproduction from nucleons can be related to transversity, the tensor charge, and other quantities related to transversity. This process isolates C-parity odd and chiral odd combinations of t-channel exchange quantum…
Exclusive electroproduction of vector mesons is a crucial way to probe QCD factorization properties. Such a factorization is up to now only proven, at the twist 2 level, for a longitudinaly polarized meson. It is crucial to extend our…
Both deeply-virtual and photoproduction of mesons offer promising access to generalized parton distributions and complementary description of different kinematical regions. The higher-order contributions offer stabilizing effect with…
The production of $D$-mesons in high-energy $pp$ collisions at the LHC kinematic regime is analyzed with the dipole approach in the momentum representation. We present predictions for the $D$-meson differential cross section in terms of the…
Exclusive $\pi^0$ electroproduction at a beam energy of 5.75 GeV has been measured with the Jefferson Lab CLAS spectrometer. Differential cross sections were measured at more than 1800 kinematic values in $Q^2$, $x_B$, $t$, and $\phi_\pi$,…
Photoproduction of a pair of particles with large invariant mass is a natural extension of collinear QCD factorization theorems which have been much studied for deeply virtual Compton scattering and deeply virtual meson production. We…