Related papers: On the non-perturbative part of the photon structu…
Interactions of virtual photons are analyzed in terms of photon structure. It is argued that the concept of parton distribution functions is phenomenologically very useful even for highly virtual photons involved in hard collisions. This…
We describe models of nonthermal photon emission from a homogeneous distribution of relativistic electrons and protons. Contributions from the synchrotron, inverse Compton, nonthermal bremsstrahlung and neutral-pion decay processes are…
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 deduce momentum sum rules for the parton structure functions of a photon target. Non-perturbative QCD contribution to the momentum sum rules follows from conservation of the energy--momentum tensor and it is calculated through the…
The parton content of real (P^2=0) and virtual (P^2\neq 0) transverse photons \gamma(P^2) is expressed in terms of perturbative pointlike and nonperturbative hadronic (VMD) components, employing recently updated parton distributions of…
Using entropic inequalities for Shannon entropies new inequalities for some classical polynomials are obtained. To this end, photon distribution functions for one-, two- and multi-mode squeezed states in terms of Hermite, Laguerre, Legendre…
We study 2-to-2 scattering amplitudes of massless spin one particles in $d=4$ space-time dimensions, like real world photons. We define a set of non-perturbative observables (Wilson coefficients) which describe these amplitudes at low…
Fluctuations of the atomic positions are at the core of a large class of unusual material properties ranging from quantum para-electricity to high temperature superconductivity. Their measurement in solids is the subject of an intense…
The nonperturbative parton distributions, obtained from the Lorentz contracted wave functions, are analyzed in the formalism of many-particle Fock components and their properties are compared to the standard perturbative distributions. We…
We present new improved parton distributions for the photon. We fit {\bf all} available data on the photon structure function, $F^{\gamma}_{2}(x,Q^2)$, with $Q^2\ge 3$ GeV$^2$, in order to determine the quark distributions. We also pay…
We develop a consistent technique for the calculation of real photon emission in hard exclusive processes, which is based on the background field formalism and allows a convenient separation of hard electromagnetic and soft hadronic…
We discuss the structure functions and the parton distributions in the virtual photon target, both polarized and unpolarized, beyond the leading order in QCD. We study the factorization-scheme dependence of the parton distributions.
We investigate the general case of the photon distribution of a two-mode squeezed vacuum and show that the distribution of photons among the two modes depends on four parameters: two squeezing parameters, the relative phase between the two…
We estimate the two-photon exchange contribution to elastic electron-proton scattering at large momentum transfer by using a quark-parton representation of virtual Compton scattering. We thus can relate the two-photon exchange amplitude to…
We first comment on the search for a deviation from the linear photon dispersion relation, in particular based on cosmic photons from Gamma Ray Bursts. Then we consider the non-commutative space as a theoretical concept that could lead to…
The photon parton distribution function (PDF) of the proton is crucial for precise comparisons of LHC cross sections with theoretical predictions. However, it was previously affected by very large uncertainties of around ${\cal O}(100\%)$…
Interactions of virtual photons are analyzed in terms of photon structure. It is argued that the concept of parton distribution functions is phenomenologically very useful even for highly virtual photons involved in hard collisions. The…
The problem of dealing with the resolved photon contribution to $P^2$-integrated $ep$ cross sections is discussed. Suitable approximations have to be found, since no parametrization of the photon structure function in the full range of…
The explicit compact expression for the susceptibility tensor of a single photon wave packet on the photon mass-shell is derived. It is assumed that the probe photon is hard, the test photon is soft, and their total energy is below the…
The QCD treatment of the photon structure is recalled. Emphasis is given to the recently derived momentum sum rule, and to the proper choice of the factorization scheme and/or boundary conditions for the evolution equations beyond the…