相关论文: Gluon and Charm Distributions in the Photon
The parton structure of the nucleon and pion is investigated in an exploratory model that allows one to assess whether the dressing of quarks can, by itself, produce realistic gluon contributions to light-cone momentum fractions,…
Parton distributions in the virtual photon target are investigated in perturbative QCD up to the next-to-next-to-leading order (NNLO). In the case $\Lambda^2 \ll P^2 \ll Q^2$, where $-Q^2$ ($-P^2$) is the mass squared of the probe (target)…
We describe the gluon parton distribution function (PDF) in the proton, deduced by data from the ATLAS and HERA experiments, in the framework of the parton statistical model. The best fit parameters involved in the Planck formula that…
Nuclear parton distribution functions are obtained by a chi^2 analysis of lepton deep inelastic experimental data. It is possible to determine valence-quark distributions at medium x and antiquark distributions at small x; however, the…
We discuss in detail the photon structure function beyond the leading logarithm approximation. Of special concern is the factorization scheme and the hadronic input; we show how to naturally absorb large terms due to the MSbar factorization…
We argue that the distribution functions for quarks and gluons are computable at small x for sufficiently large nuclei, perhaps larger than can be physically realized. For such nuclei, we argue that weak coupling methods may be used. We…
We review the latest information that is available about the parton distributions of the proton, paying particular attention to the determination of the gluon. We briefly describe the various processes that have been advocated to be a…
We have measured the probability, n(g->cc~), of a gluon splitting into a charm-quark pair using 1.7 million hadronic Z decays collected by the L3 detector. Two independent methods have been applied to events with a three-jet topology. One…
Parton distribution functions give the probability to find partons (quarks and gluons) in a hadron as a function of the fraction x of the proton's momentum carried by the parton. They are conventionally defined in terms of matrix elements…
We extend the QCD Parton Model analysis using a factorized nuclear structure model incorporating individual nucleons and pairs of correlated nucleons. Our analysis of high-energy data from lepton Deep-Inelastic Scattering, Drell-Yan and W/Z…
Charm quarks are expected to be produced mainly by the photon-gluon fusion mechanism in photon-Nucleon interactions. However, a small part of the total charm cross section originates in similar processes to those appearing in charm…
Generalized parton distributions have been introduced in recent years as a suitable theoretical tool to study the structure of the nucleon. Unifying the concepts of parton distributions and hadronic form factors, they provide a…
Fully differential heavy quark contributions to the photon structure functions in deeply inelastic scattering are computed in next-to-leading order QCD, including both the direct and resolved contributions. A variety of distributions are…
Real or virtual photons are excellent probes of nuclear structure, with a strong sensitivity to gluon distributions. Photonic reactions can be studied using ultra-peripheral collisions or at an electron-ion collider. Final states like…
We show that the charm structure functions $F^{c}_{k}$ have a hard pomeron behavior at low x, as the gluon distribution is dominated by the hard (Lipatov) pomeron at small x and all $Q^{2}$ values. It is shown that the charm structure…
We present a model based on a dipole picture with a hard and a soft pomeron in which large dipoles couple to the soft pomeron and small dipoles couple to the hard pomeron. The parameters in the model are fixed by proton-proton scattering…
Quarks and gluon, as quantum particles, are subjects to various effects that go beyond the naive parton picture and are not captured by ordinary parton densities. In this work, we investigate the twist-three parton distribution functions,…
We compute the Parton Distribution Functions (PDFs) of the unpolarised muon for the leptons, the photon, the light quarks, and the gluon. We discuss in detail the issues stemming from the necessity of evaluating the strong coupling constant…
The gluon distribution is dominated by the hard pomeron at small $x$ and all $Q^2$, with no soft-pomeron contribution. This describes well not only the DGLAP evolution of the hard-pomeron part of $F_2(x,Q^2)$, but also charm photoproduction…
The system of CCFM equations for unintegrated parton distributions in a photon is considered in the single loop approximation. We include quarks and non-singular parts of the splitting functions in the corresponding evolution equations. We…