相关论文: Small x gluon from exclusive J/psi production
The low $x$ behaviour of the gluon density $xg(x,\mu^2)$ at scale $\mu^2=2.4$ GeV$^2$ is determined using exclusive $J/\psi$ production data from HERA and LHCb within the framework of collinear factorisation at next-to-leading order (NLO).…
A leading order determination of the gluon density in the proton has been performed in the fractional momentum range $1.9 \cdot 10^{-3} < x_{g/p} < 0.18$ by measuring multi-jet events from boson-gluon fusion in deep-inelastic scattering…
The gluon density in nuclei, G^A(x), is poorly constrained at all x from the current DIS and Drell-Yan data. In this paper, we point out that J/psi production measured in proton-nucleus collisions at sqrt(s)=38.8 GeV by the E866…
We present a QCD analysis of the proton structure function $F_2$ measured by the H1 experiment at HERA, combined with data from previous fixed target experiments. The gluon density is extracted from the scaling violations of $F_2$ in the…
The current uncertainty on the gluon density extracted from the global parton analysis is large in the kinematical range of small values of the Bjorken - $x$ variable and low values of the hard scale $Q^2$. An alternative to reduces this…
A QCD analysis of jet production in deep-inelastic scattering is presented. The studies are based on recent measurements of jet cross sections in the H1 experiment at HERA which are directly sensitive to the gluon density in the proton. The…
New data, especially HERA measurements of the proton structure function at small $x$, allow the opportunity to improve our knowledge of the gluon and quark distribution functions. We perform a global analysis which incorporates these new…
Two-jet production from the direct photon contribution at HERA is a sensitive measure of the small-$x$ gluon in the proton. We propose measurements of ratios of the jet cross-sections which will clearly distinguish between gluons with or…
New, more precise data on diffractive J/psi photoproduction and on exclusive J/psi production in the process pp -> p + J/psi + p at the LHC allow a better constraint on the low-x gluon distribution in the domain of relatively low scales Q^2…
The latest measurements of $F_2$ at HERA allow for a {\it combination} of gluon and sea quark distributions at small $x$ that is significantly different from those of existing parton sets. We perform a new global fit to deep-inelastic and…
Using a recent next-to-leading-order calculation of the photoproduction double differential cross section for heavy quarks, we study the possibility of extracting the gluon density of the proton from heavy-quark photoproduction data. We…
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…
We use the LHCb data on the forward production of $D$ mesons at 7, 13 and 5 TeV to make a direct determination of the gluon distribution, $xg$, at NLO in the $10^{-5} \lesssim x \lesssim 10^{-4}$ region. We first use a simple…
In the following article we describe our measurement of the proton structure function $F_2$ and of the gluon momentum density $xg$ in $ep$ collisions with the ZEUS detector at HERA in 1993. The results for $F_2$ confirm our measurement from…
Inelastic photoproduction of $J/\psi$ particles at high energies is one of the processes to determine the gluon distribution in the nucleon. The QCD radiative corrections to the color-singlet model of this reaction have recently been…
The high density parton effects are strongly dependent of the spatial gluon distribution within the proton, with radius $R$, which cannot be derived from perturbative QCD. In this paper we assume that the unitarity corrections are present…
We present a set of formulae to extract the gluon distribution function from the deep inelastic structure function F$_2$ and its derivative dF$_2$/dlnQ$^2$ at small x in the leading and next-to-leading order of perturbation theory. The…
We investigate the nucleon and pion gluon distribution functions in the framework of holographic QCD, focusing on the small Bjorken x region. Based on an approximate relation, the gluon distributions are extracted from structure functions…
Reliable knowledge of parton distributions at large x is crucial for many searches for new physics signals in the next generation of collider experiments. Although these are generally well determined in the small and medium x range, it has…
We consider the possibility of a direct determination of the polarized gluon density in the proton using charm production with polarized beams at HERA. We study total cross sections and distributions at leading order using different…