Related papers: Diffractive Parton Distributions from Fits with Hi…
The diffractive dissociation of virtual photons, gamma*p -> Xp, has been studied in ep interactions at HERA with the H1 and ZEUS detectors. The data are presented in terms of the diffractive structure function F2D and of the diffractive…
A great interest for diffraction has been generated these last years by the HERA data. They give us the first opportunity to understand high energy diffractive physics in terms of a fundamental theory, i.e. QCD. A review of the main results…
We discuss whether the diffractive structure functions defined by current experiments at HERA are indeed probing the partonic structure function of the pomeron. We observe that the {\it pseudorapidity} cuts commonly employed require that…
The measurement of forward jet cross sections has been suggested as a promising probe of new small x parton dynamics and the question is whether the new HERA data provide an indication of this. In this paper the influence of resolved photon…
In this letter we report the direct perturbative QCD evaluation of twist-4 effects in diffractive DIS. They are large and have a strong impact on the $Q^2$ dependence of diffractive structure functions at large $\beta$. Based on the AGK…
We study a twist decomposition of diffractive structure functions in the diffractive deep inelastic scattering (DDIS) at HERA. At low Q2 and at large energy the data exhibit a strong excess, up to about 100%, above the twist 2 NLO DGLAP…
Results are given on the measurements of the hard diffractive interactions at HERA $ep$ collider. The structure of the diffractive exchange in terms of partons and the factorisation properties are discussed, in particular by comparing the…
The measurement of the polarized gluon distribution function $\Delta g(x)$ from photon gluon fusion processes in electron proton deep inelastic scattering producing two jets has been investigated. The study is based on the MEPJET simulation…
We suggest that the pseudo-rapidity cut dependence of diffractive deep-inelastic scattering events at HERA may provide a sensitive test of models of diffraction. A comparison with the experimental cross section shows that the…
The hard-gluonic contribution to the first moment of the polarized proton structure function $g_1^p(x)$ is dependent of the factorization convention chosen in defining the quark spin density and the hard cross section for photon-gluon…
Diffractive electroproduction of rho and phi mesons is measured at HERA with the H1 detector in the elastic and proton dissociative channels. The data correspond to an integrated luminosity of 51 pb^-1. About 10500 rho and 2000 phi events…
We use perturbative QCD, beyond the leading $\ln Q^2$ approximation, to show how measurements of diffractive $J/\psi$ production at HERA can provide a sensitive probe of the gluon density of the proton at small values of Bjorken $x$. We…
Parton distributions in the small $x$ region are numerically predicted by using a modified DGLAP equation with the GRV-like input distributions. We find that gluon recombination at twist-4 level obviously suppresses the rapid growth of…
Di-jet photoproduction in polarized ep collisions at HERA is studied as a possible tool to determine the parton content of circularly polarized photons. The concept of the `effective parton density' approximation is extended to the…
Recent progress on the parton distribution functions of the photon, both real and virtual, is briefly reviewed and experimental possibilities at HERA are discussed.
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…
Impact parameter dependent dipole models are ideal tools for investigating the spatial structure of the proton. We investigate the incoherent $ep$ cross section in exclusive $J/\psi$ photoproduction as measured by HERA, and find that as…
The transverse momentum distribution of the diffractive final state provides an interesting test of models of diffractive deep-inelastic scattering at HERA. We present a comparison of several colour-singlet exchange models with thrust…
Recently, a semiclassical approach to diffraction has been proposed, which treats the proton as a classical colour field. The present paper demonstrates that this approach is consistent with the concept of diffractive parton distributions.…
The distribution of the spin of the nucleon among its constituents can be parametrized in the form of polarized parton distribution functions for quarks and gluons. Using all available data on the polarized structure function $g_1(x,Q^2)$,…