Showing papers on "Parton published in 1980"
CERN1
TL;DR: In this paper, the authors developed a technique based explicitly on the factorization properties of mass singularities, which allows one to calculate the evolution of parton densities beyond leading order.
805 citations
TL;DR: In this paper, an improved perturbative QCD analysis of a wide class of hard processes is presented, including the deep inelastic lepton-hadron scattering and the inclusive e + e − annihilation to hadrons.
560 citations
CERN1
TL;DR: In this paper, the authors present a short summary of the results for the evolution of two-loop singlet parton densities for both spacelike and timelike processes.
498 citations
TL;DR: In this article, the present status of quantum chromodynamics formalism for inclusive deep-inelastic scattering is reviewed and higher-order asymptotic freedom corrections are discussed in detail.
Abstract: The present status of quantum chromodynamics formalism for inclusive deep-inelastic scattering is reviewed. Leading-order and higher-order asymptotic freedom corrections are discussed in detail. Both the formal language of operator product expansion and renormalization group and the intuitive parton model picture are used. Systematic comparison of asymptotic freedom predictions with deep-inelastic data is presented. Extensions of asymptotic freedom ideas to other processes such as massive ..mu..-pair production, semi-inclusive deep-inelastic scattering, e/sup +/e/sup -/ annihilation, and photon--photon scattering are briefly discussed. The importance of higher-order corrections is emphasized.
436 citations
TL;DR: An Introduction to Quarks and Partons by F.E. Close as discussed by the authors is a good starting point for a discussion of the relationship between quarks and partons in the context of physics.
Abstract: An Introduction to Quarks and Partons. By F.E. Close. Pp.481. (Academic: London, New York and San Francisco, 1979.) £26.40; $54.50.
261 citations
TL;DR: In this paper, a general method is explained for computing high-energy processes in gauge theories when "Sudakov double logarithms" are present, which can be applied to other processes, such as low-transverse-momentum parton phenomena, and form factors and elastic scattering of composite particles.
Abstract: A general method is explained for computing high-energy processes in gauge theories when "Sudakov double logarithms" are present. An expansion for the electron form factor in quantum electrodynamics is constructed; it gives the leading-logarithmic result of Sudakov, together with corrections to it to arbitrary logarithmic accuracy. The method can be applied to other processes, such as low-transverse-momentum parton phenomena, and form factors and elastic scattering of composite particles.
238 citations
TL;DR: In this paper, the tree-like evolution of a QCD jet in a planar gauge is studied, with particular emphasis on the soft parton region of the phase space.
137 citations
TL;DR: Most particle physicists now believe that protons, neutrons, and other strongly interacting particles are built from more basic constituents known as quarks and gluons, which interact according to the rules of a relativistic quantum field theory known as quantum chromodynamics as mentioned in this paper.
Abstract: Most particle physicists now believe that protons, neutrons, and other strongly interacting particles are built from more basic constituents known as “quarks” and “gluons,” which interact according to the rules of a relativistic quantum field theory known as “quantum chromodynamics.”
128 citations
TL;DR: In this article, a Monte Carlo model for the development of parton jets in QCD is described, and explicit low-order calculations are supplemented by leading logarithmic approximations for higher orders.
122 citations
TL;DR: In this paper, a two-chain model for soft multiparticle production in hadronic collisions is presented, which is consistent with the dual topological scheme for the Pomeron.
Abstract: We describe a two-chain model for soft multiparticle production in hadronic collisions. The model is formulated in a parton framework and is consistent with the dual topological scheme for the Pomeron. The sole inputs are valence quark structure functions in the colliding hadrons and parton fragmentation functions, both of which are known from “hard” processes. Our model, which contains no adjustable parameters, reproduces the shape, the energy dependence, and the normalization of inclusive spectra both in the central region and in the fragmentation region. The model provides a natural explanation for the ratio of πp topp cross sections.
119 citations
CERN1
TL;DR: In this paper, the effect of soft gluon emission in hard processes is examined to all orders in QCD and large corrections have been found, which sensibly modify the parton model results, and show the relevance of the appropriate kinematical limits in leptoproduction and in the Drell-Yan process.
TL;DR: In this paper, the quark and antiquark joint distribution is derived systematically with incorporation of quantum-chromodynamics ideas whenever possible, and parameters describing the distribution are determined by fitting low-$Q}^{2}$ electroproduction data.
Abstract: The low-${p}_{T}$ problem of hadron fragmentation is treated in the framework of the quark model. The basic mechanism of hadronization of quarks is recombination, which is formulated here on a firm basis. Clustering of quarks in a hadron is discussed in detail. The quark and antiquark joint distribution is derived systematically with incorporation of quantum-chromodynamics ideas wherever possible. Parameters describing the distribution are determined by fitting low-${Q}^{2}$ electroproduction data. No free parameters are therefore involved in the calculation of the pion inclusive distribution in the fragmentation region. The result agrees well with data in both shape and normalization. The formalism can be applied to calculate inclusive distributions of all nucleon- and pion-initiated reactions, while for kaon-initiated reactions it can be used to extract from low-${p}_{T}$ data the quark distributions in kaons.
TL;DR: In this article, a parton model description of small p T hadron nucleus collisions based on a two-chains Parton model for hadron-hadron collisions is presented.
TL;DR: In contrast to the recently discovered large quantum-chromodynamics (QCD) correction to the Drell-Yan formula, a certain quark-parton model relation between structure functions for lepton pair production is not subject to any first-order QCD modification as discussed by the authors.
Abstract: It is pointed out that, in contrast to the recently discovered large quantum-chromodynamics (QCD) correction to the Drell-Yan formula, a certain quark-parton-model relation between structure functions for lepton pair production is not subject to any first-order QCD modification. Both parallelism and contrast to the Callan-Gross relation in deep-inelastic scattering are spelled out. Implications on the lepton angular distribution for both low and high q/sub perpendicular/ are discussed. The case is made that this relation provides a unique opportunity to test the ''QCD-improved quark-parton model.''
TL;DR: The production in hadron collisions of a pair of virtual photons, each having a large invariant mass, proceeds via two mechanisms: (a) two independent Drell-Yan-type annihilations of quark pairs in a single interaction and (b) the pair annihilation process qq-bar..--> gamma..*..gamma..* as discussed by the authors.
Abstract: The production in hadron collisions of a pair of virtual photons, each having a large invariant mass, proceeds via two mechanisms: (a) two independent Drell-Yan-type annihilations of quark pairs in a single interaction and (b) the pair annihilation process qq-bar..--> gamma..*..gamma..*. We argue that both mechanisms allow intriguing tests of constituent structure and its associated scaling laws and we show that, despite their ..cap alpha../sup 4/ production rate, events of this type are accessible with existing ..pi.. and proton beams.
TL;DR: In this paper, the transverse momentum distributions for inclusive proton-proton interactions were studied in terms of the parton model and quantum chromodynamics, and the results were interpreted in terms both of the Parton Model and Quantum Chromodynamics.
Abstract: The transverse momentum distributions are studied for inclusive proton-proton interactions. The results are interpreted in terms of the parton model and quantum chromodynamics. (AIP)
TL;DR: In this article, the authors derived expressions for the angular energy flow and the energy-energy angular pattern in perturbative QCD, to order αs, and showed explicitly their infrared safety.
TL;DR: In this article, a large solid angle apparatus consisting of a superconducting solenoid magnet, cylindrical drift chambers and two arrays of lead-glass counters was used to examine particles associated with a high transverse momentum trigger in p-p collisions with three s values at the CERN ISR.
TL;DR: In this article, a formalism is proposed which incorporates event vetos to separate hard-scattering jets from spectator jets in high-p/sub T/ hadron collisions.
Abstract: We evaluate those processes in perturbative quantum chromodynamics which can lead to the production of three high-p/sub T/ jets in hadron-hadron collisions. A formalism is proposed which incorporates event vetos to separate hard-scattering jets from spectator jets. These vetos modify the scaling violations of the initial parton distribution functions. A simple estimate indicates that the three-jet fraction in high-p/sub T/ hadron processes may be up to four times larger than the corresponding three-jet fraction in e/sup +/e/sup -/ annihilation.
TL;DR: In this paper, the point-like nature of the photon-quark interaction gives rise to a new class of hard-scattering subprocesses so that the high-p}_{T}$ events will consist of both three and four-jet topologies.
Abstract: High-${p}_{T}$ jet photoproduction can serve as a source of new information not obtainable with hadron beams alone. The pointlike nature of the photon-quark interaction gives rise to a new class of hard-scattering subprocesses so that the high-${p}_{T}$ events will consist of both three- and four-jet topologies. The separation of these two contributions, which can be done on a purely kinematic basis, leads to new tests of the underlying dynamics. Further, by using quantum chromodynamics it is possible to calculate the parton distribution functions of the photon without any phenomenological input parametrizations. This fact can be exploited in the development of techniques for enhancing the fraction of quark-jet or gluon-jet triggers which, in turn, may be of use in searching for differences between quark and gluon jets. Detailed cross-section predictions together with estimates of backgrounds and sources of theoretical uncertainty are presented.
TL;DR: In this paper, it was shown that in axial gauge QCD the dominant diagrams in the leading logarithm approximation have a ladder structure and the non-singlet ladders were used to obtain the angular distribution of quark/antiquark jets in the γγ c.m.
TL;DR: In this article, a simple space-time description of high-energy hadron-nucleus collisions is presented, based on the two-sheet description of soft multiparticle production in hadronhadron collisions, and can be formulated in a parton framework.
Abstract: A simple space-time description of high-energy hadron-nucleus collisions is presented. The model is based on the two-sheet description of soft multiparticle production in hadron-hadron collisions, and can be formulated in a parton framework. This zero-parameter model agrees well with the general features of hadron-nucleus data. 3 figures.
TL;DR: In this paper, a parton model interpretation of the cut vertex formalism was proposed, which extends to all orders in the running coupling constant α(t), the Altarelli-Parisi picture in both the time-like and space-like regions.
TL;DR: In this paper, the charge correlations of particles in an event with a large p T triggering particle have been investigated applying a new method, which has been developed for non-diffractive inelastic hadronic events.
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TL;DR: In this article, a fragmentation mechanism was proposed to interpret in a parton framework the Pomeron contribution which dominates high-energy low-P}-T$ hadronic reactions.
Abstract: We propose a fragmentation mechanism to interpret in a parton framework the Pomeron contribution which dominates high-energy low-${P}_{T}$ hadronic reactions. We successfully compare our predictions to experimental data on one-particle inclusive distributions. We derive a pure parton expression of the Pomeron contribution which clarifies the theoretical understanding of high-energy interactions.
TL;DR: In this article, a quarkparton model of a nucleus viewed in a high-momentum frame was proposed and used to calculate lepton scattering, lepton pair production, W-boson production, particle production at large x and small p/sub T/, and cumulative production of particles at backward angles in high-energy hadron-nucleus collisions.
Abstract: We propose a quark-parton model of a nucleus viewed in a high-momentum frame. We use it to calculate deep-inelastic lepton scattering, lepton pair production, W-boson production, particle production at large x and small p/sub T/, and cumulative production of particles at backward angles in high-energy hadron-nucleus collisions. Predictions are compared with experimental data. Good agreement between theory and experiment is demonstrated.
TL;DR: In this article, an analysis of the most recent data for R(e/sup +/e/ sup -/..-->.. hadrons) using improved theoretical techniques is presented, showing that the data lie about 15-17 % above the theory; the experimental uncertainty is +- 10% (dominated by systematics).
Abstract: A careful analysis is presented of the most recent data for R(e/sup +/e/sup -/ ..-->.. hadrons) using improved theoretical techniques. The analysis is based on a generalized method for smoothing R. We show why the hadronic cross section is potentially one of the best tests of quantum chromodynamics. The theoretical complications such as unknown parameters and nonperturbative corrections are discussed, and resulting theoretical uncertainties are estimated. Some previously neglected QED corrections are accounted for. We find that for ..sqrt..s-bar near 7 GeV, the data lie about 15--17 % above the theory; the experimental uncertainty is +- 10% (dominated by systematics). For ..sqrt..s-bar near 5 GeV, the difference is only 5--8 %. This apparent discrepancy may well be due to systematic problems in the experiment. For completeness we consider the possibility that there is a threshold for new particles at ..sqrt..s-bar approx. = 6 GeV. We consider new quarks, Higgs bosons, color-sextet quarks, integrally charged and even fractionally charged leptons. While most of these hypotheses are not particularly attractive, some cannot be ruled out.
TL;DR: In this article, a relativistic impulse approximation model is proposed to estimate the scaling behavior of few-body nuclei in the preasymptotic regions of an infinite-momentum frame.
TL;DR: In this article, the evolution of parton distributions in high-energy scattering is described using the methods of branching processes, and the multiplicity distribution of partons with momenta above a given cutoff is calculated from a functional form of the evolution equations.