Related papers: Evolution at small x
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…
In the semiclassical approach, inclusive and diffractive quark and gluon distributions are expressed in terms of correlation functions of Wilson loops. Each Wilson loop integrates the colour field strength in the area between the…
The paper presents the $QCD$ description of the hard and semihard processes in the framework of the Wilson operator product expansion. The smooth transition between the cases of the soft and hard Pomerons is obtained.
We derive an equation determining the small-x evolution of the F_2 structure function of a large nucleus which includes all multiple pomeron exchanges in the leading logarithmic approximation using Mueller's dipole model. We show that in…
The transition from the low $Q^2$ region in deep inelastic scattering where charm production is described by photon-gluon fusion to a region where the charm structure function $F_2^c$ is largely generated by a charm quark density should be…
Coherence phenomena, and the non-universality of parton structure of the effective Pomeron are explained. New hard phenomena directly calculable in QCD such as diffractive electroproduction of states with $M^2\ll Q^2$ as well as new options…
Holographic soft-wall model is successful in the phenomenology of hadrons. Here with the use of generalized parton distributions (GPDs) obtained from AdS/QCD, perturbative effects are entered into the formalism. Perturbations are…
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…
A new approach to global QCD analysis is developed. The main ingredients are two QCD-based evolution equations. The first one is the Balitsky-Kovchegov nonlinear equation, which sums higher twists while preserving unitarity. The second…
This is a draft describing the calculation of the evolution of the gluon density in $x$ from an initial value $x=x_{0}=0.01$ to smaller values, up to $x=10^{-8}$ in the hard pomeron formalism with a running coupling introduced on the basis…
Power-suppressed corrections to parton evolution may affect the theoretical accuracy of current determinations of parton distributions. We study the role of multigluon-exchange terms in the extraction of the gluon distribution for the Large…
We present a QCD analysis of the proton structure function $F_2$ measured by the H1 experiment at HERA, combined with data from previous fixed target experiments. The gluon density is extracted from the scaling violations of $F_2$ in the…
A precise proton structure function F_2 at low x is measured. The data is interpreted in the framework of QCD with an extraction of gluon density xg. The charm contribution to F_2 is determined in an extended kinematic range. Neutral and…
The deep-inelastic deuteron structure function (SF) $F_2^D(x_D,Q^2)$ in the covariant approach in light-cone variables is considered. The $x_D$ and $Q^2$-dependences of SF are calculated. The QCD analysis of generated data both for…
I present a theoretical discussion of the uncertainties related to the QCD analysis of the proton structure function $F_2(x,Q^2)$ at small $x$. The role played by the `unphysical' gluon density is pointed out. It is shown how the study of…
In this paper, the evolutions of longitudinal proton structure function have been obtained at small-$x$ up to next-to-next-to-leading order using a hard Pomeron behavior. In our paper, evolutions of gluonic as well as heavy longitudinal…
The paper presents the QCD description of the small $x$ behaviour of parton distribution functions in the leading twist of Wilson operator product expansion. The smooth transition between the cases of the soft and hard Pomerons is obtained.…
We review the parton model and the Regge approach to the QCD description of the deep-inelastic $ep$ scattering at the small Bjorken variable $x$ and demonstrate their relation with the DGLAP and BFKL evolution equations. It is shown, that…
We present exploratory studies of the proton structure via two distinct kinds of gluon densities: the transverse-momentum dependent functions, whose evolution is determined by the CSS equation, and the unintegrated gluon distribution, whose…
We investigate the Q^2 evolution of parton distributions at small x values, recently obtained in the case of soft initial conditions. The results are in excellent agreement with deep inelastic scattering experimental data from HERA.