相关论文: Perturbative evolution at small x
We perform a global parton analysis of deep inelastic and related hard-scattering data, including ${\cal O}(\alpha_{\rm QED})$ corrections to the parton evolution. Although the quality of the fit is essentially unchanged, there are two…
We investigate an alternative to the DGLAP evolution of structure functions through the use of Fixed Order Perturbation Theory. Remarkable agreement between the two methods are found in the polarized sector for a wide $x$, $Q^2$ region.…
The perturbative QCD fragmentation functions can be applied phenomenologically as a model for charm and bottom quark fragmentation into heavy-light mesons. The predictions by this model on the observables $P_V$ and $\langle z \rangle$ for…
We present numerical studies of the leading non-linear corrections to the DGLAP evolution equations of parton distribution functions (PDFs) resulting from gluon recombination, which reduce the pace of evolution at small momentum fractions…
We investigate the evolution of parton densities at small values of the momentum fraction, x, by including resummed anomalous dimensions in the renormalization group equations. The resummation takes into account the leading-logarithmic…
We present an introductory discussion of deep-inelastic lepton-proton scattering as a means to probe the substructure of the proton. A resume of QCD is given, emphasizing the running of the coupling constant and the DGLAP evolution…
The DGLAP and CCFM approaches to perturbative QCD evolution have been investigated by examining correlations of charmed hadron pairs in $pp$ collisions at $\sqrt{s}=7$ TeV. The theoretical models are compared to the data taken by the LHCb…
$Q^2$ evolution of structure functions in the nucleon and nuclei is investigated by using usual DGLAP equations and parton-recombination equations. Calculated results for proton's $F_2$ and for the ratio $F_2^{Ca}/F_2^D$ are compared with…
We discuss the causes which can limit the accuracy of the predictions based on the conventional PDFs when including in global parton analyses the data at moderate scales $\mu$. The first is the existence of power corrections ${\cal O}…
We consider the fragmentation of heavy quarks into heavy-flavoured hadrons, specifically the production of charmed mesons in $e^+e^-$ collisions, at different centre-of-mass energies. We focus our attention on the ratio of moments of the…
We develop two approaches to the problem of soft fragmentation of hadrons in a gauge theory for high energy processes. The first approach directly adapts the standard resummation of the parton distribution function's anomalous dimension…
We present microscopic QCD calculation of the cross section of diffractive DIS and of the partonic structure of the pomeron from the dipole approach to the generalized BFKL pomeron. We show that the pomeron can not be treated as a particle…
The Berger model of perturbative fragmentation of quarks to pions is improved by providing an absolute normalization and keeping all terms in a (1-z) expansion, which makes the calculation valid at all values of fractional pion momentum z.…
Various implications of new, non-perturbative pomeron inspired enhancement of small-x neutrino-nucleon structure functions for high-energy neutrino astrophysics are discussed. At x larger than 10^{-5} these functions are given by…
In a previous paper, we have shown that it was possible to use the DGLAP evolution equatio n to constrain the high-$Q^2$ ($Q^2 \ge 10$ GeV$^2$) behaviour of the residues of a high-e nergy Regge model, and we applied the developed method to…
We study the interface between soft and hard QCD at high energy and small momentum transfer. At LHC and SSC energies, we find that a cutoff BFKL equation leads one to expect a measurable perturbative component in traditionally soft…
Double hard scattering in proton-proton collisions is described in terms of double parton distributions. We derive bounds on these distributions that follow from their interpretation as probability densities, taking into account all…
New structure-function data are in excellent agreement with the existence of a hard pomeron, with intercept about 1.4. It gives a very economical description of the data. Having fixed 2 parameters from the data for the real-photon cross…
Employing the representation of the experimental data on deep inelastic electron-proton scattering (DIS) in the color-dipole picture (CDP), we determine the gluon distribution of the proton at small Bjorken $x$. At sufficiently large…
In the high energy regime, the proton structure consists of a very large number of particles called partons (quarks and gluons) that interact with each other, according to the theory of strong interactions, Quantum Chromodynamics (QCD).…