QED radiative corrections to impact factors

We consider the radiative corrections to the impact factors of electron and photon. According to a generalized eikonal representation the e\bar e scattering amplitude at high energies and fixed momentum transfers is proportional to the electron form factor. But we show that this representation is violated due to the presence of non-planar diagrams. One loop correction to the photon impact factor for small virtualities of the exchanged photon is obtained using the known results for the cross section of the e\bar e production at photon-nuclei interactions.Comment: 8 pp, plain LaTe

Vector Meson Production in Ultraperipheral Heavy Ion Collisions

The ultraperipheral heavy ion collisions (UPC's) are an important alternative to study the QCD dynamics until the next generation of $e^+e^-/ ep / eA$ colliders become reality. Due to the coherent action of all the protons in the nucleus, the electromagnetic field is very strong and the resulting flux of equivalent photons is large, which allows to study two-photon as well as photonuclear interactions at high energies. In this paper we present a brief review of the vector meson production in UPC's at high energies using the QCD color dipole approach to describe their photonuclear production and the perturbative QCD Pomeron (BFKL dynamics) to describe the double meson production in photon-photon process. Predictions for rates and integrated cross sections are presented for energies of RHIC and LHC.Comment: 16 pages, 1 figure. Version to be published in Journal of Physics G: Nuclear and Particle Physic

Asymptotic behavior of double parton distribution functions

The double parton distribution functions are investigated in the region of small longitudinal momentum fractions in the leading logarithm approximation of perturbative QCD. It is shown that these functions have the factorization property in the case of one slow and one fast parton.Comment: 7 pages, revtex

Double parton scattering in double logarithm approximation of perturbative QCD

Using the explicit form of the known single distribution functions (the Green's functions) in the double logarithm approximation of perturbative QCD, we analyze the structure of splitting diagrams as a source of double parton perturbative correlations in the proton. The related phenomenological effects are discussed for the conditions of the LHC experiments.Comment: 8 pages, 1 figure, Refs. and explanations added, published version (Phys. Rev. D

A fresh look at double parton scattering

A revised formula for the inclusive cross section for double parton scattering in terms of the modified collinear two-parton distributions extracted from deep inelastic scattering is suggested. The possible phenomenological issues are discussed.Comment: 6 pages, 2 figures, revtex4, discussion slightly modified, 3 references adde

Four point function of R-currents in N=4 SYM in the Regge limit at weak coupling

We compute, in N=4 super Yang-Mills theory, the four point correlation function of R-currents in the Regge limit in the leading logarithmic approximation at weak coupling. Such a correlator is the closest analog to photon-photon scattering within QCD, and there is a well-defined procedure to perform the analogous computation at strong coupling via the AdS/CFT correspondence. The main result of this paper is, on the gauge theory side, the proof of Regge factorization and the explicit computation of the R-current impact factors.Comment: 21 pages, 10 figures, typos correcte

Deep inelastic scattering and prompt photon production within the framework of quark Reggeization hypothesis

We study ep deep inelastic scattering and the inclusive production of prompt photon within the framework of the quasi-multi-Regge-kinematic approach, applying the quark Reggeization hypothesis. We describe structure functions F_2 and F_L supposing that a virtual photon scatters on a Reggeized quark from a proton, via the effective gamma-Reggeon-quark vertex. It is shown that the main mechanism of the inclusive prompt photon production in p \bar p collisions is the fusion of a Reggeized quark and a Reggeized antiquark into a photon, via the effective Regeon-Reggeon-gamma vertex. We describe the inclusive photon transverse momentum spectra measured by the CDF and D0 Collaborations within errors and without free parameters, using the Kimber-Martin-Ryskin unintegrated quark and gluon distribution functions in a proton.Comment: 13 pages, 10 figure

QED peripheral mechanism of pair production at colliders

Cross section of the processes of neutral pion production as well as pairs of charged fermions and bosons in peripherical interaction of leptons, photons are calculated in main logarithmical approximation. We investigate the phase volumes and differential cross sections. The differential cross section of few neutral pions and a few pairs production are written down explicitly. Considering the academic problem of summation on the number of pairs for the case of massless particles we reproduce the known results obtained in seventies of last century. The possibility to construct the generator for Monte-Carlo modeling of this processes basing of this results are discussed.Comment: 25 pages, 5 figure

Lessons from All Logs Summation in Yukawa Theories

Some features of old results in the total summation of all logarithmic contributions of all diagrams in Yukawa theory are presented. We discuss some lessons from this picture for the description of Pomeron, odderon, etc. in QCD.Comment: 6 pages, 2 figure

Study of non-collinear parton dynamics in the prompt photon photoproduction at HERA

We investigate the prompt photon photoproduction at HERA within the framework of kt-factorization QCD approach. Our consideration is based on the off-shell matrix elements for the underlying partonic subprocesses. The unintegrated parton densities in a proton and in a photon are determined using the Kimber-Martin-Ryskin (KMR) prescription. Additionally, we use the CCFM-evolved unintegrated gluon as well as valence and sea quark distributions in a proton. A conservative error analisys is performed. Both inclusive and associated with the hadronic jet production rates are investigated. The theoretical results are compared with the recent experimental data taken by the H1 and ZEUS collaborations. We study also the specific kinematical properties of the photon-jet system which are strongly sensitive to the transverse momentum of incoming partons. Using the KMR scheme, the contribution from the quarks emerging from the earlier steps of the parton evolution is estimated and found to be of 15 - 20 approximately.Comment: 22 pages, 13 figures, 2 tabl