We study the systematic inclusion of QED corrections in the evolution of parton distributions. O(α) corrections modify the evolution equation for parton distributions. They introduce additional parton distributions, like the photon distribution in the nucleon, and lead to additional mixing effects. We discuss the modifications for a realistic model of Nf,up up-type flavours and Nf,down down-typ...

We study the generalized parton distributions, including the helicity-flip ones, using Nambu-Jona-Lasinio model based on a relativistic Faddeev approach with ‘static approximation’. Sum rules relating the generalized parton distributions to nucleon electromagnetic form factors are satisfied. Moreover, quark-antiquark contributions in the region −ξ < x < ξ are non-vanishing. Our results are qual...

In view of the start up of the 14 TeV pp Large Hadron Collider the quark anti−quark reactions leading to the final states WW, WZ and ZZ are studied, in the frame work of the Standard Model (SM), using helicity amplitudes. The differential and total cross sections are first evaluated in the parton-parton center of mass system and then transformed to their expected structure in pp collisions thro...

Lorentz invariance relations connecting twist-3 parton distributions with transverse momentum dependent twist-2 distributions have been proposed previously. These relations can be extracted from a covariant decomposition of the quark-quark correlator. It is argued, however, that the derivation of the Lorentz invariance relations fails if the path-ordered exponential is taken into account in the...

Kinetic theory is used to check the applicability of parton cascade in 1 dimensional expansion. Using the information provided by 3 dimensional parton cascade, we model the transverse expansion by an effective area. With this model, kinetic theory is able to give prediction of the time development of transverse energy which is in good agreement with the parton cascade results. ∗This work was su...

Assuming the proton’s light-cone wave function to be dominated by small parton virtualities and small intrinsic transverse momenta, we show that the electroproduction amplitudes at large momentum transfer factorize into parton-level subprocess amplitudes and form factors representing 1/xmoments of skewed parton distributions. On the basis of a wave function overlap model for the form factors we...

The end-point contributions in the quark longitudinal momentum fraction of the virtual photon (γ) to vector meson (V ) impact factor to the diffractive electroproduction amplitude can be factorized in terms of a generalized parton evolution of the target parton distribution. The result is used to model the helicity amplitudes γp → V p in terms of small x generalized parton distributions. e-mail...

We introduce a Monte Carlo space-time model for high-energy collisions with nuclei, involving the dynamical interplay of perturbative QCD parton production and evolution, with non-perturbative parton-cluster formation and ‘afterburner’ cascading of formed pre-hadronic clusters plus hadron excitations. This approach allows us to trace the space-time history of parton and hadron degrees of freedo...

1 The simplest Poissonian model A standard way to introduce multiple parton interactions in Montecarlo codes is to assume a Poissonian distribution of multiple parton collisions, with average number depending on the value of the impact parameter. The motivations were discussed long ago in several articles [1] [2] [3]: One introduces the three dimensional parton densityD(x, b), namely the averag...