Related papers: Nonperturbative \gamma^* p Interaction in the Diff…
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…
We derive the forward photoproduction amplitude for the diffractive $\gamma p \to l^+ l^- p$ reaction in the momentum space. within the formalism of $k_\perp$- factorization. Predictions for the $\gamma p \to l^+ l^- p$ reaction are given…
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…
Using a set of new odderon states, we calculate their contribution to the diffractive eta_c photo- and electroproduction process. Compared to previous simple 3-gluon exchange calculations we find an enhancement of about one order of…
The diffractive photoproduction of J/psi mesons is measured with the H1 detector at the ep collider HERA using an integrated luminosity of 78 pb^-1. The differential cross section d sigma(gamma p -> J/psi Y) / d t is studied in the range 2…
The Q^2 dependence of inclusive electron-proton scattering F_2 structure function data in both the nucleon resonance region and the deep inelastic region, at momentum transfers below 5 (GeV/c)^2, is investigated. Moments of F_2 are…
We investigate the QED Compton process (both elastic and inelastic) in unpolarized and longitudinally polarized electron-proton scattering. The cross section can be expressed in terms of the equivalent photon distribution of the proton. We…
Hard diffractive electroproduction of longitudinally polarized vector mesons is calculated within the leading $\alpha_s\ln{Q^2\over\Lambda_{QCD}^2}$ approximation of QCD using the leading order parton densities within the nucleon. Novel QCD…
The total hadronic gamma*gamma* cross sections at high energy are calculated as a function of energy and photon virtuality in a model combining Regge exchange, the quark box diagram (a fixed pole in Regge language) and soft and hard pomeron…
We emphasize the importance of tagging the outgoing forward protons to sharpen the predictions for New Physics at the LHC (such as the diffractive production of a light Higgs boson). The rescattering effects lead to a rich distinctive…
It is reported on an analysis of electroproduction of light mesons at small Bjorken-x within the handbag approach. The partonic subprocesses, meson electroproduction off quarks or gluons, are calculated within the modified perturbative…
The cross section for exclusive heavy quark and heavy antiquark pair ($Q \bar Q$) production in peripheral ultrarelativistic heavy ion collisions is calculated for the LHC energy $\sqrt{s_{NN}}$ = 5.5 TeV. Here we consider only processes…
The amplitude for production of a single photon associated with quark pair in the fusion of two off-shell gluons is calculated. The matrix element found is applied to the inclusive prompt photon hadroproduction at high energies in the…
In this letter we address issues involved in quarkonium production near the boundaries of phase space. It is shown that higher-order non-perturbative contributions are enhanced in this kinematic region and lead to a breakdown of the…
Characteristics of hadron production in diffractive deep-inelastic positron-proton scattering are studied using data collected in 1994 by the H1 experiment at HERA. The following distributions are measured in the centre-of-mass frame of the…
The diffractive process $\gamma p\to V + X$ (where $V$ is a vector meson and $X$ results from the dissociation of the proton) is studied. In particular, we consider the region of large momentum transfer (i.e. $|t|\gg\Lambda_{QCD}^2$) and…
The results of a measurement of the proton structure function F_2(x,Q^2)and the virtual photon-proton cross section are reported for momentum transfers squared Q^2 between 0.35 GeV^2 and 3.5 GeV^2 and for Bjorken-x values down to 6 10^{-6}…
We argue that hadron production in coherent diffraction of proton on a heavy nucleus provides a very sensitive probe of the low-x QCD dynamics. This process probes the BFKL dynamics in proton and the non-linear gluon evolution in nucleus.…
The differential cross sections \sigma_0=\sigma_T+\epsilon \sigma_L, \sigma_{LT}, and \sigma_{TT} of \pi^0 electroproduction from the proton were measured from threshold up to an additional center of mass energy of 40 MeV, at a value of the…
A large data set of charged-pion 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…