Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userThe colour dipole approach to small-x processes
72
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We explain why it is possible to formulate a wide variety of high energy (small-x) photon-proton processes in terms of a universal dipole cross section and compare and contrast various parameterizations of this function that exist in the literature.
rate research
Read More
We present a method to include colour-suppressed effects in the Mueller dipole picture. The model consistently includes saturation effects both in the evolution of dipoles and in the interactions of dipoles with a target in a frame-independent way. When implemented in a Monte Carlo simulation together with our previous model of energy--momentum conservation and a simple dipole description of initial state protons and virtual photons, the model is able to reproduce to a satisfactory degree both the gamma*-p cross sections as measured at HERA as well as the total p-p cross section all the way from ISR energies to the Tevatron and beyond.
The connection between multiparton interaction, diffractive processes and saturation effects is discussed. The relation of the rise of the gluon density at small longitudinal momentum fractions x with the occurrence of saturation, diffraction and multiparton interaction is being studied both experimentally and theoretically. We illustrate key ideas underlying recent progress, and stress the role of different theoretical approaches to small-x QCD evolution in investigations of multiparton interactions.
We investigate small$-x$ resummation effects in QCD coefficient functions for $Z_0g$ and $Wg$ fusion processes, and we compare them with the known ones of $gamma g$ type. We find a strong process dependence, that we argue to be due to the possible presence of collinear singularities for either small or large $k$ of the exchanged gluon. For top quark production, we find that the $ggra tbar{t}$ and $Z_0gra tbar{t}$ channels have larger resummation enhancements than the $Wgra tbar{t}$ one.
A personal summary of the discussions which took place at the informal meeting in Amirim, Israel from June 1-4 2000, concerning the dipole picture of small-$x$ physics is presented. The broad aim of the meeting was to address the question ``Has HERA reached a new QCD regime (at small $x$) ?. The new regime in question is the high-density, but weak-coupling, limit of perturbative QCD.
Over the past few years considerable progress has been made on the resummation of double-logarithmically enhanced threshold (large-x) and high-energy (small-x) higher-order contributions to the splitting functions for parton and fragmentation distributions and to the coefficient functions for inclusive deep-inelastic scattering and semi-inclusive e^+e^- annihilation. We present an overview of the methods which allow, in many cases, to derive the coefficients of the highest three logarithms at all orders in the strong coupling from next-to-next-to-leading order results in massless perturbative QCD. Some representative analytical and numerical results are shown, and the present limitations of these resummations are discussed.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
