Related papers: HERA data and DGLAP evolution: theory and phenomen…
Using QCD motivated and phenomenological considerations, we construct x- dependent polarized parton distributions, which evolve under GLAP evolution, satisfy DIS data and are within positivity constraints. Each flavor is done separately and…
It is shown that exact, amplitude-based resummation allows IR-improvement of the usual DGLAP theory. This results in a new set of kernels, parton distributions and attendant reduced cross sections, so that the QCD perturbative result for…
In the current region of semi-inclusive deep-inelastic scattering, most events are accompanied by intensive radiation of soft and collinear partons which cannot be reliably described at any fixed order of perturbative QCD. In this paper, a…
We study the effects of next-to-leading order corrections on the evolution of the twist-two non-forward parton distribution functions in the flavour non-singlet sector. It is found that the deviation from leading order evolution is small…
The kinematic region covered by the LHC experiments probes low values of Bjorken-$x$. At the scale relevant for $W$ and $Z$ production the central rapidity region covers $10^{-3} < x < 10^{-1}$. This means that it is the HERA data which…
The HERAPDF2.0 ensemble of parton distribution functions (PDFs) was introduced in 2015. The final stage is presented, a next-to-next-to-leading-order (NNLO) analysis of the HERA data on inclusive deep inelastic $ep$ scattering together with…
We estimate the cross-section and asymmetry relevant for the production of forward jets in polarised deep inelastic scattering in the region of small values of $x$ which can be probed at possible polarised HERA measurements. The kinematical…
We review recent developments in the determination of parton densities from deep inelastic and related data. We show how the asymmetries observed in the W+- rapidity distributions and in pp/pn Drell-Yan production further constrain the…
A recent proposal seeks to explain the anomaly in the HERA high-Q^2 neutral current e^+p data by modifying the parton distribution functions at moderate-to-high-x and large Q^2. We investigate the consequences of this proposal for the HERA…
The standard analytic solution to the DGLAP equation in Mellin space is improved by resumming the large x divergences. Explicit results are given to next-to-leading order and next-to-leading logarithmic accuracy. Numerically, the…
Higher twist corrections to the structure function F_2 at small x are studied for the case of a flat initial condition for the twist-two QCD evolution in the next-to-leading order approximation. We present an analytical parameterization of…
In this contribution, I present a new QCD fit to final combined HERA deep-inelastic scattering cross-section data incorporating $\ln(1/x)$-resummation terms. This fit has been performed within the xFitter framework. The main effect of…
We study the Q^2 evolution of parton distributions at small x values, obtained in the case of flat initial conditions. The contributions of twist-two and (renormalon-type) higher-twist operators of the Wilson operator product expansion are…
Diffractive parton distributions of the proton are determined from fits to diffractive data from HERA. In addition to the twist--2 contribution, the twist--4 contribution from longitudinally polarised virtual photons is considered, which is…
We present a set of formulas to extract two second-order independent differential equations for the gluon and singlet distribution functions. Our results extend from the LO up to NNLO DGLAP evolution equations with respect to the…
In this paper t and x-evolutions of gluon distribution function from Dokshitzer-Gribov-Lipatov-Altarelli-Parisi(DGLAP) evolution equation in leading order(LO) at low-x, assuming the Regge behaviour of quark and gluon at this limit, are…
Parton recombination is reconsidered in perturbation theory without using the AGK cutting rules in the leading order of the recombination. We use time-ordered perturbation theory to sum the cut diagrams, which are neglected in the GLR…
We use the Bessel-inspired behavior of the structure function F2 at small x, obtained for a flat initial condition in the DGLAP evolution equations. We fix the scale of the coupling constant, which eliminates the singular part of anomalous…
We introduce a new parametrization for the parton distribution functions (PDFs) designed to be flexible in the small-x region. We implement it in the xFitter open-source PDF fitting tool, and compare it to the default xFitter…
We compare the parton distributions deduced in the framework of a quantum statistical approach for both the longitudinal and transverse degrees of freedom with the unpolarized distributions measured at Hera and with the polarized ones…