Showing papers on "Parton published in 1981"
TL;DR: In this paper, a review of modern perturbative aspects of QCD is critically reviewed from a theoretical as well as phenomenological point of view, including the classical more formal approach of summing leading logs.
485 citations
TL;DR: In this article, a parton model interpretation of the predictions of quantum chromodynamics in the process e+e−→hadron + anything was presented and the complete list of parameters needed for the study of the scaling violations of fragmentation functions up to the next-to-leading logarithmic approximation was given.
239 citations
TL;DR: In this article, a partial review of QCD at high energies is given Factorization and the use of the renormalization group equation are emphasized Topics discussed are the parton model, cut vertices in covariant and axial gauges, μ-pair production, jets, form factors, x → 1 limit of structure fu nctions, wide angle elastic scattering and heavy quarkonium exclusive decays.
237 citations
TL;DR: In this paper, the role of partons with momenta much less than the c.m. energy is studied in general n-particle inclusive annihilation cross sections, and the cancellation of non-factorizing logarithms associated with these partons is demonstrated in physical gauges.
115 citations
TL;DR: In this article, the authors describe hadron-nucleus interactions at small PT in the framework of a dualparton model which is a generalization of the two-chain dual-partonmodel of hadron interactions introduced recently in the literature.
Abstract: We describe hadron-nucleus interactions at smallPT in the framework of a dual-parton model which is a generalization of the two-chain dual-partonmodel of hadron-hadron interactions introduced recently in the literature. The model (of a multiple scattering type) is formulated in the framework of the 1/N expansion in dual theories. Regge singularities are used to determine the (joint) momentum distribution functions of the various sets of constituents (valence and sea quarks) which yield hadron jets in successive orders of the 1/N expansion. These jets result from a standard color separation mechanism, inspired by QCD. We study the inclusive spectra of various types of secondaries for various projectiles and targets. Particular emphasis is laid on theA-dependence in the projectile fragmentation region. A comparison with available experimental data is presented.
111 citations
TL;DR: In this article, data on hadron production by e+e−−-annihilation at c.m. energies between 30 GeV and 36 GeV are presented and compared with two models both based on first-order QCD but using different schemes for the fragmentation of quarks and gluons into hadrons.
95 citations
TL;DR: The O(..cap alpha/sub s/) perturbative quantum-chromodynamic corrections to weak, charged-current production of heavy quarks are evaluated in this article, and the residual corrections to the flavor-production structure functions are shown to be modest except for x'..-->..1 or Q/sup 2/..cc-bar splitting ''singularities'' into evolution of an intrinsic charm-sea component of the nucleon.
Abstract: The O(..cap alpha../sub s/) perturbative quantum-chromodynamic corrections to weak, charged-current production of heavy quarks are evaluated. For perturbative subtractions and parton densities defined via the electroproduction structure function F*/sub 2/, the residual corrections to ..nu..N flavor-production structure functions are shown to be modest except for x'..-->..1 or Q/sup 2/ ..cc-bar splitting ''singularities'' into evolution of an intrinsic charm-sea component of the nucleon. The longitudinal structure function due to charm production is computed and found to be substantial.
74 citations
TL;DR: A description of the origin of the polarization asymmetry in terms of Thomas precession of the quarks' spins in the recombination process accounts for all of the qualitative features of the baryon and antibaryon polarization data.
Abstract: The parton-recombination model plus SU(6) symmetry is used to relate polarizations in inclusive baryon production to those of the underlying constituent subprocesses. A description of the origin of the polarization asymmetry in terms of Thomas precession of the quarks' spins in the recombination process accounts for all of the qualitative features of the baryon and antibaryon polarization data.
70 citations
TL;DR: In this paper, a systematic method of calculating twist-4 corrections, based on the operator product expansion in QCD, is described and applied to the lowest moment of the transverse structure function in electroproduction.
68 citations
CERN1
TL;DR: In this article, the mass (M), infrared (IR), and ultraviolet (UV) divergences of the (double) cut graphs with the methods exposed in paper I. The correction terms are explicitly shown to be independent of any regularization method.
63 citations
TL;DR: In this article, the authors present the prescription for calculating the jet calculus vertices to higher orders, and give complete results for the quark decay probabilities in the next-to-leading approximation.
TL;DR: In this paper, the multiplicity distributions of charged hadrons produced in νp interactions are studied using a sample of 7850 charged current interactions in BEBC, and a comparison is made with other lepton and hadron-induced reactions.
CERN1
TL;DR: In this paper, the QCD αs corrections to the single-lepton spectrum in the process hadron + hadron→W±, Z0 or γ→l± + anything are analyzed using two different factorization prescriptions and numerical results are shown for two different parton distribution parametrizations.
TL;DR: In this article, the authors measured the differential cross-sections for the vector and tensor mesons using various parametrizations for they and the dependence of their differential cross sections.
Abstract: Inclusive production of ϱ0,f, andg
0 mesons and ofK
0
,K
*0 (892), ϕ andK
*0(1430)mesons has been measured at ∼2.6 and
∼1.1 GeV/c in proton-proton interactions at $$\sqrt s = 52.5$$ GeV. The negative particle from the two-body decays of these resonances were identified by a threshold Cerenkov counter and used for triggering. Starting from the measured differential cross section, total inclusive cross sections for the vector and tensor mesons were determined using various parametrizations for they andp T dependence of the differential cross section. The experimental results are discussed in the framework of production models based on the parton picture. The strangeness suppresion factor λ=(0.30±0.10) due toSU(3) symmetry breaking of the quark sea is derived.
TL;DR: In this paper, the predictions of perturbative QCD for a number of areas of hadron dynamics are discussed, including exclusive processes at large momentum transfer, the endpoint behavior of hadronic structure functions, and the Fock state structure of wavefunctions.
Abstract: The predictions of perturbative QCD for a number of areas of hadron dynamics are discussed, including exclusive processes at large momentum transfer, the endpoint behavior of hadronic structure functions, and the Fock state structure of hadron wavefunctions-especially their behavior at short-distance. New results for exclusive two-photon processes, the normalization of higher twist contributions to the meson structure function, and the calculation of the valence Fock state probability of the pion are presented. We also review the contrasting features of QCD and parton model dynamics.
TL;DR: In this article, the structure functions of the nucleon are analyzed in the valon model in which a nucleon is assumed to be a bound state of three valence quark clusters (valons).
Abstract: Structure functions of the nucleon are analyzed in the valon model in which a nucleon is assumed to be a bound state of three valence quark clusters (valons). At high Q/sup 2/ the structure of the valons is described by leading-order results in the perturbative quantum chromodynamics. From the experimental data on deep-inelastic scattering off protons and neutrons, the flavor-dependent valon distributions in the nucleon are determined. Predictions for the parton distributions are then made for high Q/sup 2/ without guesses concerning the quark and gluon distributions at low Q/sup 2/. The sea-quark and gluon distributions are found to have a sharp peak at very small x. Convenient parametrization is provided which interpolates between different numbers of flavors.
TL;DR: In this paper, the inclusive reactions h+p→φ+X, (h=π±,,K±,p±) are studied for 0⪅xF⪆0.3 and p⊥ ⩽ 1 GeV at 93 and and 63 GeV incident momentum.
TL;DR: In this article, it is shown that the evolution of hadronic jets produced in hard processes can be studied in terms of a simple parton branching picture, beyond the leading log approximation of QCD.
TL;DR: In this article, the parton-recombination model plus SU(6) symmetry is used to relate polarizations in inclusive baryon production to those of the underlying constituent subprocesses.
Abstract: The parton-recombination model plus SU(6) symmetry is used to relate polarizations in inclusive baryon production to those of the underlying constituent subprocesses. A large number of predictions are given, none of which disagrees with experiment. It is suggested that the polarization arises via Thomas precession of the quarks' spins in the recombination process. This description accounts for all of the qualitative features of the baryon and antibaryon polarization data.
TL;DR: In this article, a comprehensive review of the polarization asymmetries predicted by QCD and the parton model for hard processes is given, and the validity of the formulae derived and the potential effects of non-leading logarithmic and power orders are discussed.
Abstract: We give a comprehensive review of the polarization asymmetries predicted by QCD and the parton model for hard processes. The article discusses the interrelation between these processes which include deep inelastic inclusive, massive lepton pairs, reflected and transmitted asymmetries in hadron production at large pT, prompt photon production, etc. We also discuss the validity of the formulae derived and the potential effects of non-leading logarithmic and power orders.
CERN1
TL;DR: In this article, the gluon radiative corrections to parton processes producing lepton pairs at large transverse momentum are calculated, and the corrections bring theory into better agreement with the data.
TL;DR: In this article, a measurement of direct production of electron pairs of masses below 1.3 GeV in proton-nucleus collisions at 13 GeV/c has been performed using a two-arm spectrometer.
TL;DR: In this article, the authors present results on hadronic production in antineutrino-proton interactions in terms of both their exclusive channel components and the deep-inelastic part of the data, for which the total hadronic mass W and the lepton four-momentum transfer Q/sup 2/ are large.
Abstract: In this paper we present results on hadronic production in antineutrino-proton interactions. The data sample, which consists of 2033 charged-current events with antineutrino energy above 5 GeV, comes from exposures of the 15-foot hydrogen bubble chamber to the Fermilab broad-band antineutrino beam. The results are discussed in terms of both their exclusive-channel components and the deep-inelastic part of the data, for which the total hadronic mass W and the lepton four-momentum transfer Q/sup 2/ are large. The current-quark fragmentation shows properties in good agreement with the simple quark-parton model. In particular, the data show no evidence for scaling violations or breakdown of the factorization hypothesis when the selections appropriate to obtaining the current-quark fragments are used. The jetlike features of the events and the energy and charge correlations in the quark fragmentation region are in reasonable agreement with the standard jet model of Field and Feynman. However, these features and the transverse-momentum properties of the current-quark fragments also follow phase-space predictions. The characteristics of the spectator-diquark (target fragmentation) system are presented. These features are compared to those of the current-quark system and to some predictions of quark-fusion models for proton fragmentation.
TL;DR: In this paper, the authors studied the performance of charged pion production in an exposure of BEBC, filled with hydrogen, to an incidentK ≥ 70 GeV/c.
Abstract: Inclusive charged pion production is studied in an exposure of BEBC, filled with hydrogen, to an incidentK
+ beam of 70 GeV/c. Total cross sections for pion production and inclusive longitudinal and transverse momentum distributions of π−'s and of positive particles are presented and compared with data at lower energies. Earlier evidence for scaling in the fragmentation regions is confirmed. The central region π− cross section increases proportionally top
LAB
−1/4
; positive particles show almost no energy dependence atx=0. Particle ratios π+/π− are studied as a function ofx andy
* and a comparison with 70 GeV/cK
−
p data is made. Analysis of structure functions for (ππ) pairs and of particle production associated with π± triggers at large |x| in the context of quark/parton models, provides qualitative evidence for the diquark-quark structure of the proton.
TL;DR: In this paper, the absolute p ⊥ -distributions for Drell-Yan pairs produced in π N and pN collisions are studied in perturbative QCD and found in excellent agreement with data.
TL;DR: In this paper, the longitudinal and other polarization dependent cross sections for jet production in deep inelasticep, vp, and p, and====== ��\bar vp$$¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ scattering up to order α s¯¯¯¯ of the quark-gluon coupling constant were calculated.
Abstract: We have calculated the longitudinal and other polarization dependent cross sections for jet production in deep inelasticep, vp, and
$$\bar vp$$
scattering up to order α
s
of the quark-gluon coupling constant. Fragmentation of final state partons into hadrons is taken into account. Distributions in thrust,p
2
in
andp
2
out
are predicted for all three reactions and various values ofW andQ.
TL;DR: In this paper, the authors calculate charmed quark spectra resulting from the QCD evolution of parton distributions which enter into the contributions of peripheral parton subprocesses to pp → Λ c + + X.
CERN1
TL;DR: In this paper, a Monte Carlo method is presented for the calculation of the QCD evolution of structure functions and its application is discussed in detail in the framework of the LLA, but it can also be used with modified parton decay probability functions including higher order effects.
TL;DR: In this paper, a double logarithmic quark form factor was derived for both hadronic production of lepton pairs and e/sup +/e/sup -/ annihilation.
Abstract: Perturbative quantum chromodynamic corrections involving the emission of gluons that are both soft and collinear are discussed for both hadronic production of lepton pairs and e/sup +/e/sup -/ annihilation. The result is an exponential, double logarithmic quark form factor. The differences between previous analyses are clarified, and the possible experimental observation of the form factor is discussed and illustrated. 9 figures, 1 table.