Related papers: The Photon Structure Function at Small-x
A model for the longitudinal structure function $F_L$ at low $x$ and low $Q^2$ is presented, which includes the kinematical constraint $F_L \sim Q^4$ as $Q^2 \rightarrow 0$. It is based on the photon-gluon fusion mechanism suitably…
First attempts are described to determine the unintegrated Parton Density Function of the gluon from a fit to measurements of the structure function $F_2(x,Q^2)$ and also $F_2^c(x,Q^2)$ measured at HERA. Reasonable descriptions of both…
We investigate target mass effects in the unpolarized virtual photon structure functions $F_2^\gamma(x,Q^2,P^2)$ and $F_L^\gamma(x,Q^2,P^2)$ in perturbative QCD for the kinematical region $\Lambda^2 \ll P^2 \ll Q^2$, where $-Q^2(-P^2)$ is…
Photon structure derives from quantum fluctuation in quantum field theory to fermion and anti-fermion, and has been an experimentally established feature of electrodynamics since the discovery of the positron. In hadronic physics, the…
The pion structure function is investigated in a simple model, where pion and constituent quark fields are coupled through the simplest pseudoscalar coupling. The imaginary part of the forward gamma* pi-> gamma* pi scattering amplitude is…
Q$^2$ variation of the nuclear-structure-function ratio $F_2^A(x,Q^2)/F_2^D(x,Q^2)$ is investigated in a parton model with Q$^2$-rescaling and parton-recombination effects. Calculated results are compared with the NMC (New Muon…
A recent reanalysis of world proton and deuteron structure function measurements showed that a significant amount of the apparent model dependence in the extraction of the neutron structure function was related to inconsistencies between…
Low Q2 photon-proton cross sections are analysed using a simple, QCD-motivated parametrisation $\sigma_{\gamma^\star p}\propto 1/(Q^2+Q_0^2)$, which gives a good description of the data. The Q2 dependence of the gamma* p cross section is…
Recent experimental results contributing to the understanding of the structure of the nucleon are reviewed. They include the final NMC results on proton and deuteron structure functions; a re-analysis of the CCFR data on F2 and xF3; new…
We present a fully analytic computation of the complete electron and photon structure functions, or QED lepton parton distribution functions (PDFs) up to two-loop order. Our computation is performed using modern techniques of reduction to…
At high energies photon-photon interactions are dominated by quantum fluctuations of the photons into fermion-antifermion pairs and into vector mesons. This is called photon structure. Electron-positron collisions at LEP are an ideal…
We review small $x$ contributions to perturbative evolution equations for parton distributions, and their resummation. We emphasize in particular the resummation technique recently developed in order to deal with the apparent instability of…
We present parametrizations for the proton structure function $F_2$ in the next to leading order in perturbative QCD. The calculations show that the dominant term to $F_2(x,Q^2)$ should grow as $x^{-\ls}$ for small $x$ values, with the…
The isoscalar structure functions $xF_3$ and $F_2$ are measured as functions of $x$ averaged over all $Q^2$ permissible for the range of 6 to 28 GeV of incident neutrino (anti-neutrino) energy at the IHEP-JINR Neutrino Detector. The QCD…
The production of final state photons in hadronic $Z$-boson decays can be used to study the quark-to-photon fragmentation function $D_{q\to \gamma}(z,\mu_{F})$. Currently, two different observables are used at LEP to probe this function:…
Nuclear modification of the structure function $F_3$ is investigated. Although it could be estimated in the medium and large $x$ regions from the nuclear structure function $F_2^A$, it is essentially unknown at small $x$. The nuclear…
We re-examine the large-x neutron/proton structure function ratio extracted from the latest deuteron data, taking into account the most recent developments in the treatment of Fermi motion, binding and nucleon off-shell effects in the…
A measurement of the proton structure function $F_{\!2}(x,Q^2)$ is reported for momentum transfer squared $Q^2$ between 4.5 $GeV^2$ and 1600 $GeV^2$ and for Bjorken $x$ between $1.8\cdot10^{-4}$ and 0.13 using data collected by the HERA…
We introduce a saturation model for photon-photon interactions, based on a QCD dipole picture of high energy scattering. The two-dipole cross-section is assumed to satisfy the saturation property. This pomeron-like contribution is…
Nuclear effects in deep inelastic scattering at low$-x$ are phenomenologically described changing the typical dynamical and/or kinematical scales characterizing the free nucleon case. In a holographic approach, this rescaling is an…