Quark-Hadron Duality in Spin Structure Functions $g_1^p$ and $g_1^d$ PDF Download
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Languages : en
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New measurements of the spin structure functions of the proton and deuteron g1{sup p}(x, Q2) and g1{sup d}(x, Q2) in the nucleon resonance region are compared with extrapolations of target-mass-corrected next-to-leading-order (NLO) QCD fits to higher energy data. Averaged over the entire resonance region (W 2 GeV), the data and QCD fits are in good agreement in both magnitude and Q2 dependence for Q2 1.7 GeV2/c2. This ''global'' duality appears to result from cancellations among the prominent ''local'' resonance regions: in particular strong [sigma]{sub 3/2} contributions in the [Delta](1232) region appear to be compensated by strong [sigma]{sub 1/2} contributions in the resonance region centered on 1.5 GeV. These results are encouraging for the extension of NLO QCD fits to lower W and Q2 than have been used previously.
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Languages : en
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New measurements of the spin structure functions of the proton and deuteron g1{sup p}(x, Q2) and g1{sup d}(x, Q2) in the nucleon resonance region are compared with extrapolations of target-mass-corrected next-to-leading-order (NLO) QCD fits to higher energy data. Averaged over the entire resonance region (W 2 GeV), the data and QCD fits are in good agreement in both magnitude and Q2 dependence for Q2 1.7 GeV2/c2. This ''global'' duality appears to result from cancellations among the prominent ''local'' resonance regions: in particular strong [sigma]{sub 3/2} contributions in the [Delta](1232) region appear to be compensated by strong [sigma]{sub 1/2} contributions in the resonance region centered on 1.5 GeV. These results are encouraging for the extension of NLO QCD fits to lower W and Q2 than have been used previously.
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Languages : en
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Jefferson Lab experiment E01-012 measured the He-3 spin-structure functions and virtual photon asymmetries in the resonance region in the momentum transfer range 1.0
Author: Simonetta Liuti
Publisher: World Scientific
ISBN: 9814478490
Category : Science
Languages : en
Pages : 298
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Book Description
While perturbative QCD methods fully describe experimental results at high energies, and chiral perturbation theory is the low energy effective theory of the strong interactions, a form of duality is observed connecting these two regimes. In these intermediate kinematics, a wide variety of reactions are observed which can be described simultaneously by single particle (quark) scattering, and by exclusive resonance (hadron) scattering.The contributions in this proceedings volume discuss recent and existing results, and aim to foster current and future research, investigating the phenomenon of quark-hadron duality.This unique volume contains research work by scientists from different arenas of hadronic physics, dealing with different manifestations of quark-hadron duality.
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Languages : en
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Quark-Hadron duality has been experimentally demonstrated for the spin independent structure function F2. Duality is observed when, at the same value of scaling variable x{sub bj}, the smooth scaling curve at high momentum transfer becomes an average over the resonances at lower momentum transfer. Jefferson Lab experiment 01-012 used the polarized 3He target in Hall A for an extraction of the neutron spin structure function g1(superscript n) and the virtual photon asymmetry A1(superscript n) in the resonance region over a Q2 range from 1.0 to 4.0 (GeV/c)2. Data from E01-012 combined with Deep Inelastic Scattering data will provide a test of quark-hadron duality predictions for g1(superscript n) and A1(superscript n). This will be one of the first tests of the spin and flavor dependence of quark-hadron duality. The demonstration of duality for spin structure functions will enable us to use the resonance data to study the nucleon spin structure in the large x{sub bj} region.
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Languages : en
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One of the biggest challenges in the study of the nucleon structure is the understanding of the transition from partonic degrees of freedom to hadronic degrees of freedom. In 1970, Bloom and Gilman noticed that structure function data taken at SLAC in the resonance region average to the scaling curve of deep inelastic scattering (DIS). Early theoretical interpretations suggested that these two very different regimes can be linked under the condition that the quark-gluon and quark-quark interactions are suppressed. Substantial efforts are ongoing to investigate this phenomenon both experimentally and theoretically. Quark-hadron duality has been confirmed for the unpolarized structure function F2 of the proton and the deuteron using data from the experimental Hall C at Jefferson Lab (JLab). Indications of duality have been seen for the proton polarized structure function g1 and the virtual photon asymmetry A1 at JLab Hall B and HERMES. Because of the different resonance behavior, it is expected that the onset of duality for the neutron will happen at lower momentum transfer than for the proton. Now that precise spin structure data in the DIS region are available at large x, data in the resonance region are greatly needed in order to test duality in spin-dependent structure functions. The goal of experiment E01-012 was to provide such data on the neutron (3He) in the moderate momentum transfer (Q2) region, 1.0
Author: Alessandra Fantoni
Publisher: World Scientific
ISBN: 9812774130
Category : Science
Languages : en
Pages : 298
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Book Description
While perturbative QCD methods fully describe experimental results at high energies, and chiral perturbation theory is the low energy effective theory of the strong interactions, a form of duality is observed connecting these two regimes. In these intermediate kinematics, a wide variety of reactions are observed which can be described simultaneously by single particle (quark) scattering, and by exclusive resonance (hadron) scattering. The contributions in this proceedings volume discuss recent and existing results, and aim to foster current and future research, investigating the phenomenon of quark-hadron duality. This unique volume contains research work by scientists from different arenas of hadronic physics, dealing with different manifestations of quark-hadron duality. Sample Chapter(s). Chapter 1: Introductory Remarks on Duality in Lepton-Hadron Scattering (490 KB). Contents: Introduction and Review: Experimental and Theoretical Status: Duality in the Polarized Structure Functions (H P Blok); Spin Structure of the Nucleon and Aspects of Duality (Z E Meziani); Duality and Confinement: Quark Models of Duality in Electron and Neutrino Scattering (W Melnitchouk); Hadron Structure on the Back of an Envelope (A W Thomas et al.); Spin-Flavor Decomposition and in Polarized Semi-Inclusive Deep Inelastic Scattering Experiments at Jefferson Lab (X Jiang); Duality in Photoproduction: Duality in Vector-Meson Production (A Donnachie); Onset of Scaling in Exclusive Processes (M Mirazita); Duality in Nuclei: A Partonic Picture of Jet Fragmentation in Nuclei (X-N Wang); Quark Gluon Plasma and Hadronic Gas on the Lattice (M P Lombardo); Duality in Neutrino Experiments: Neutrinos and Local Duality (F Steffens & K Tsushima); Duality and QCD: Higher Twist Effects in Polarized DIS (E Leader et al.); Highly Excited Hadrons in QCD and Beyond (M Shifman); Future Perspectives: Transverse Polarization and Quark-Hadron Duality (O V Teryaev); Research Perspectives with the Jefferson Lab (K de Jager); Perspectives with PANDA (P Gianotti); Summary Talk (P Hoyer); and other papers. Readership: Researchers, academics and lecturers in high energy, particle and nuclear physics.
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Languages : en
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We review recent progress in the study of quark-hadron duality in electron-nucleon structure functions. New developments include insights into the local aspects of duality obtained using truncated moments of structure functions, which allow duality-violating higher-twist contributions to be identified in individual resonance regions. Preliminary studies of pion electropro-duction have also showed the first glimpses of duality in semi-inclusive cross sections, which if confirmed would greatly expand the scope of constraining the flavor and spin dependence of parton distributions.
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I review recent developments in the study of quark-hadron duality in inclusive electron scattering in the resonance-scaling transition region. Results on matrix elements of twist-4 operators extracted from moments of the spin-dependent g1 structure function suggest that duality violating higher twists are small above Q2 (almost equal to) 1 GeV2. The systematics of the x dependence of local duality are analyzed within a quark model framework, and mechanisms are identified for spin-flavor symmetry breaking which underpin the behavior of structure functions at large x.
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Languages : en
Pages : 182502
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We present experimental results of the first high-precision test of quark-hadron duality in the spin-structure function g_1 of the neutron and $^3$He using a polarized 3He target in the four-momentum-transfer-squared range from 0.7 to 4.0 (GeV/c)^2. Global duality is observed for the spin-structure function g_1 down to at least Q^2 = 1.8 (GeV/c)^2 in both targets. We have also formed the photon-nucleon asymmetry A_1 in the resonance region for 3He and found no strong Q^2-dependence above 2.2 (GeV/c)^2.
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We apply a model for the study of quark-hadron duality in inclusive electron scattering to the calculation of spin observables. The model is based on solving the Dirac equation numerically for a scalar confining linear potential and a vector color Coulomb potential. We qualitatively reproduce the features of quark-hadron duality for all potentials considered, and discuss the onset of scaling and duality for the responses, spin structure functions, and polarization asymmetries. Duality may be applied to gain access to kinematic regions which are hard to access in deep inelastic scattering, namely for x{sub Bj} --> 1, and we discuss which observables are most suitable for this application of duality.
