Showing papers on "Parton published in 1983"
TL;DR: In this paper, an iterative cascade-based model for string dynamics is described, which is based on a cascade-fly model using string dynamics, with tunneling in a constant force field.
2,060 citations
TL;DR: In this article, the effects of parton-parton interactions (screenings), that stop the increase of the cross sections near their unitarity limit, and the coherent emission of soft gluons by the global colour charge of whole groups of harder particles, are studied in detail.
1,955 citations
TL;DR: In this paper, a method of deriving the first power corrections (1/Q 2 ) to the leptoproduction structure functions is presented, based directly on the manipulation of Feynman diagrams, in which the transverse components of momenta and the gluon field control both kinematic and dynamical power corrections.
243 citations
TL;DR: In this paper, all O(1/Q2) corrections to leptoproduction are described by a small number of generalized multiparton distribution functions which depend only on the longitudinal momentum of the partons.
172 citations
TL;DR: In this paper, a QCD model for e+e− annihilation is presented, and its consequences are compared with experimental data, which involves production of a shower of partons described by a simple approximation to QCD perturbation theory, and decay of colour singlet clusters of produced partons into hadrons through a simple phase space process.
127 citations
TL;DR: In this paper, the dimensionally regularized two-loop Feynman diagrams were used to contribute to the electromagnetic form factor of an on-shell quark in massless quantum chromodynamics.
Abstract: Analytic results are presented for the dimensionally regularized two-loop Feynman diagrams which contribute to the electromagnetic form factor of an on-shell quark in massless quantum chromodynamics.
119 citations
Book•
01 Jun 1983
106 citations
TL;DR: In this paper, it was shown that the error due to unknown dynamical (higher-twist) corrections to the QCD parton model is small provided an isoscalar target is used.
92 citations
TL;DR: In this paper, the internal spin structure of the nucleon has been studied in the context of deep inelastic scattering, which has played a central role in establishing the quark-parton theory of the composition of hadrons and of quantum chromodynamics (QCD).
Abstract: The study of the structure of the proton and neutron through deep inelastic scattering, initially with electrons but subsequently with muons and neutrinos as well, has played a central role in establishing the quark-parton theory of the composition of hadrons and of quantum chromodynamics (QCD). One important aspect of these theoretical and experimental developments is the two spin-dependent structure functions, which are independent of the two spin-averaged structure functions and define the internal spin structure of the nucleon. Since both quarks and gluons possess spin and the forces between them are spin dependent, we can expect important information on these forces and on nucleon structure to be obtained through the study of the spindependent aspects of the nucleon wave function, as has been the case before in atomic and nuclear physics.
84 citations
TL;DR: In this article, all the one-loop corrections to the Drell-Yan process in QCD, including gluon exchanges involving spectator partons, were studied, and weak factorization at measured dimuon Q T was demonstrated.
83 citations
TL;DR: In this article, the production of single mesons and opposite side pairs of mesons in hadron-nucleus and nucleus nucleus collisions is calculated in the framework of the QCD parton model, with the assumption that quarks and gluons undergo multiple scattering in the nucleus.
Abstract: Production of single mesons and opposite side pairs of mesons in hadron-nucleus and nucleusnucleus collisions are calculated in the framework of the QCD parton model, with the assumption that quarks and gluons undergo multiple scattering in the nucleus. A comparison with all available data is made. It is also shown that the anomalous nuclear enhancement, especially its dependence on the flavour, can be quantitatively described within the model. Furthermore, we predict no enhancement for symmetric pairs as it seems to be indicated by the data. Predictions for largep
T production in α−α scattering at ISR are made.
TL;DR: In this paper, the recently proposed model of Field and Wolfram for e+e− annihilation, which describes hadronization without using fragmentation functions, is examined and enlarged, which provides a more sensible separation of long and short distance physics.
TL;DR: In the last five years ample evidence has been found supporting the idea that the quark-parton structure of hadrons is relevant for multiple production in soft hadronic collisions as mentioned in this paper.
Abstract: In the last five years ample evidence has been found supporting the idea that the quark-parton structure of hadrons is relevant for multiple production in soft hadronic collisions. Starting from the experimental foundations, the authors compare the most successful models applying this idea. Implications are discussed on special type reactions like diffraction dissociation and collisions on nuclei, and the models are confronted with recent data leading to new insight and modifications. Relative yields of particles in the central region may be understood as reflecting their valence quark structure in the framework of quark combinatorics, and the comparison of the valence structure of initial and final hadrons allows one to understand yields in the fragmentation regions. From the structure functions of initial hadrons and/or the fragmentation functions of (di)quarks into final hadrons as seen in deep inelastic lepton-hadron or e+e- collisions, one can deduce the shape of fragmentation spectra in soft hadronic collisions. However, hadronic oscillations also prove a very rich independent source of information on parton structure. Work to be done on the theoretical side is on a solid foundation of the two successful pictures of quark fragmentation and quark recombination as well as on an explanation of their apparent complementarity. On the experimental side, apart from further results from the pp collider, high statistics is needed on hydrogen and on heavier nuclei at rho lab>200 GeV/c in particular from strange beams.
TL;DR: In this article, low-order electromagnetic corrections to deep inelastic scattering of polarized leptons by polarized nucleons are derived and investigated using a covariant method, and the sensitivity of the corrections to the choice of the structure functions is investigated.
TL;DR: In this paper, the KNO multiplicity distributions and properties of two-particle correlations in QCD jets are considered in the framework of the perturbative approach accounting for effects of the coherence in the soft gluon bremsstrahlung.
Abstract: The KNO multiplicity distributions and properties of two-particle correlations in QCD jets are considered in the framework of the perturbative approach accounting for effects of the coherence in the soft gluon bremsstrahlung.
TL;DR: In this article, the authors estimate ψψ production at collider energies in the framework of perturbative QCD, using the O(α 2 )−(α 4 ) parton cross-sections, with the non-relativistic approximation for the heavy quark bound states.
Abstract: We estimate ψψ production at collider energies in the framework of perturbative QCD. TheO(α
2
)−(α
4
) parton cross-sections, with the non-relativistic approximation for the heavy quark bound states, are used. This first insight into the characteristics of the kinematical distributions allows predictions on the predominance of the quark, gluon orB meson production mechanisms in particular kinematical regions.
TL;DR: In this paper, the important difference between deep inelastic muon scattering off iron and that off deuterium, was explained by a reduced Fermi motion of the quarks bound in iron.
TL;DR: In this paper, the Drell-Yan parton distribution functions P q / A (x, k T ) are related by a light cone expansion to the distribution functions measured in deeply inelastic lepton scattering.
TL;DR: In this paper, the forward-backward rapidity correlation slope in the dual parton model is measured in different rapidity intervals, which yields direct information on multiple-scattering, and it turns out that the particles produced in inelastic rescattering are concentrated neary=0.
Abstract: We study the forward-backward rapidity correlation slope in
$$\bar p$$
p interactions at high energies. We show that the measurement of this slope in different rapidity intervals, yields direct information on multiple-scattering. It turns out that the particles produced in inelastic rescattering are concentrated neary=0. This is a key feature of the multi-chain dual parton model, and leads to a simple explanation of the main features of multi-hadron production at very high energies, such as the energy dependence of the height and shape of the rapidity distribution, approximate K.N.O. scaling etc. We also show that the large values of the forward-backward correlation slope measured at ISR and SPS, are obtained in the model using the standard idea of short-range order in a single inelastic collision.
TL;DR: In this paper, the authors studied the distribution of particles within and between jets of 3-jet final states produced in the reactione+e−→hadrons at c.m. energies of 22 GeV and 29-36.4 GeV.
Abstract: We have studied the distribution of particles within and between jets of 3-jet final states produced in the reactione+e−→hadrons at c.m. energies of 22 GeV and 29–36.4 GeV. The lowest energy jet shows distributions of transverse momenta, particle flow, and energy flow which differ significantly from those of the other two jets and from jets of 2-jet events atEcm=14 GeV. First order QCD calculations with subsequent fragmentation of quarks and gluons into hadrons indicate that the lowest energy jet has the largest probability of originating from a gluon. To reproduce the observed differences in an independent parton fragmentation model, the secondary quarks of a gluon jet have to have higher transverse momenta and lower parallel momenta than those of a quark jet. The particle densities between the jets as well as the correlation of transverse and longitudinal momenta of the particles within the jets favour models with fragmentation along the colour axes.
TL;DR: Using a parametric representation for Feynman integrals, it was shown in this article that the generalized momenta of the k -body composite operators have spectral properties necessary for their parton interpretation.
CERN1
TL;DR: In this paper, it was shown that the number of successive parton interactions is not the only relevant factor for equilibrium formation, another factor being the early randomization present in all experiments which observe a subsystem of the complete final state and average over many unobserved degrees of freedom.
Abstract: This paper addresses two questions concerning the hydrodynamical approach to high energy collisions producing large multiplicities of hadrons. The first one concerns the difficulty of understanding in terms of successive parton interactions the formation of local thermal equilibrium for the small and short-lived blobs of excited hadronic matter created in such collisions. We argue that the number of successive parton interactions is not the only relevant factor for equilibrium formation, another factor being the early randomization present in all experiments which observe a subsystem of the complete final state and average over many unobserved degrees of freedom. This conjecture helps to understand the high degree of universality of hadronic jets and the fact that quite different dynamical models manage to describe the same data. The second problem concerns the hadronization of a blob of quark-gluon plasma as could be produced in a very high energy collision. Assuming the transition of plasma to hadron gas to have high latent heat, we show for small chemical potential that the plasma can deflagrate and convert a fraction of its latent heat into collective flow of the hadron gas. In such deflagrations very little entropy is produced, but the flow velocity of the hadron gas with respect to the plasma can be more than half of the velocity of light.
CERN1
TL;DR: In this article, the O( α 2 s )−O( α 4 s ) parton cross sections for ψ ψ production by quarks, gluons and B mesons were determined in the framework of perturbative QCD.
TL;DR: In this paper, the authors measured at PETRA the process e γ → e + hadrons at an average Q 2 value of 9 GeV 2 / c 2, and the total number of observed events attributed to this process is 215.
TL;DR: Recently determined gluon and other parton distributions are used and higher order [ O ( α 3 S )] perturbative corrections (K -factors) are taken into account in this article.
TL;DR: In this article, the rapidity distribution of fast fragments of scattered partons has been measured in events triggered on a π + of large transverse momentum, p T > 4 GeV/ c.
CERN1
TL;DR: In this article, the transverse angular distribution of the charm pairs and of the ψψ pairs produced in hadronic collisions is calculated assuming the partons within the initial hadrons to have transverse momentum.
Abstract: Assuming the partons within the initial hadrons to have transverse momentum we have calculated in the framework of the fusion process the transverse angular distributions of the charm pairs and of the ψψ pairs produced in hadronic collisions. The transverse angle is defined as
$$\cos \phi = P_{T3} \cdot P_{T4} /(|P_{T3} ||P_{T4} |)$$
wherep
T3 andp
T4 are the transverse momenta of the charm pairs/ψψ pairs. By comparing with the data we find that the effective transverse momentum of the partons is ∼ 0.6 GeV/c.
TL;DR: In this paper, it was shown that particle ratios in the central region of p p and p p collisions give valuable information on the fate of valence quarks in a soft hadronic collision.
TL;DR: In this article, the contribution of the mechanism (II) is dominant for an extensive range of the energy although that of mechanism (I) increases rapidly with energy, while both mechanisms give comparable contributions in l± N processes.
Abstract: Higgs boson productions are studied in high energy lI( i7)N and l± N scatterings. Total cross· sections are calculated at the lowest order of perturbation by taking into account two kinds of mechanisms, i. e., bremsstrahlungs from (I) strange· and charm· quark and from (II) W±, Z boson, and detailed numerical results are presented in the framework of QCD improved parton model. In liN process, it is shown that the contribution of the mechanism (II) is dominant for an extensive range of the energy although that of the mechanism (I) increases rapidly with energy. On the contrary, both mechanisms give comparable contributions in l± N processes. The total cross·sections are found to be rather small for both reactions even at very high energy.
CERN1
TL;DR: In this paper, the leading-order QCD predictions for three-jet production at collider energies were calculated using 2 → 3 parton subprocesses and the p⊥ spectrum of jets was calculated.