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Title: Moments of nuclear and nucleon structure functions at low Q{sup 2} and the momentum sum rule

Abstract

New nuclear structure function data from Jefferson Lab covering the higher-x and lower-Q{sup 2} regime make it possible to extract the higher-order F{sub 2} moments for iron and deuterium at low four-momentum transfer squared Q{sup 2}. These moments allow for an experimental investigation of the nuclear momentum sum rule and a direct comparison of the nonsinglet nucleon moment with lattice QCD results.

Authors:
 [1];  [2];  [3];  [3];  [4]
  1. James Madison University, Harrisonburg, Virginia 22807 (United States)
  2. Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
  3. Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23602 (United States)
  4. (United States)
Publication Date:
OSTI Identifier:
20771485
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 73; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevC.73.045206; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; CEBAF ACCELERATOR; COMPARATIVE EVALUATIONS; DEUTERIUM; DEUTERONS; FOUR MOMENTUM TRANSFER; IRON; LATTICE FIELD THEORY; NUCLEAR STRUCTURE; NUCLEONS; QUANTUM CHROMODYNAMICS; STRUCTURE FUNCTIONS; SUM RULES

Citation Formats

Niculescu, I., Arrington, J., Ent, R., Keppel, C.E., and Hampton University, Hampton Virginia 23668. Moments of nuclear and nucleon structure functions at low Q{sup 2} and the momentum sum rule. United States: N. p., 2006. Web. doi:10.1103/PhysRevC.73.045206.
Niculescu, I., Arrington, J., Ent, R., Keppel, C.E., & Hampton University, Hampton Virginia 23668. Moments of nuclear and nucleon structure functions at low Q{sup 2} and the momentum sum rule. United States. doi:10.1103/PhysRevC.73.045206.
Niculescu, I., Arrington, J., Ent, R., Keppel, C.E., and Hampton University, Hampton Virginia 23668. Sat . "Moments of nuclear and nucleon structure functions at low Q{sup 2} and the momentum sum rule". United States. doi:10.1103/PhysRevC.73.045206.
@article{osti_20771485,
title = {Moments of nuclear and nucleon structure functions at low Q{sup 2} and the momentum sum rule},
author = {Niculescu, I. and Arrington, J. and Ent, R. and Keppel, C.E. and Hampton University, Hampton Virginia 23668},
abstractNote = {New nuclear structure function data from Jefferson Lab covering the higher-x and lower-Q{sup 2} regime make it possible to extract the higher-order F{sub 2} moments for iron and deuterium at low four-momentum transfer squared Q{sup 2}. These moments allow for an experimental investigation of the nuclear momentum sum rule and a direct comparison of the nonsinglet nucleon moment with lattice QCD results.},
doi = {10.1103/PhysRevC.73.045206},
journal = {Physical Review. C, Nuclear Physics},
number = 4,
volume = 73,
place = {United States},
year = {Sat Apr 15 00:00:00 EDT 2006},
month = {Sat Apr 15 00:00:00 EDT 2006}
}
  • New nuclear structure function data from Jefferson Lab covering the higher x and lower Q{sup 2} regime make it possible to extract the higher order F{sub 2} moments for iron and deuterium at low four-momentum transfer squared Q{sup 2}. These moments allow for an experimental investigation of the nuclear momentum sum rule and a direct comparison of the non-singlet nucleon moment with Lattice QCD results.
  • The Gerasimov-Drell-Hearn sum rule is used to demonstrate that the polarization structure function of the neutron approaches the asymptotic regime at Q{sup 2}=2 GeV{sup 2}. For Q{sup 2}>1.5 GeV{sup 2}, the deviation of the polarization structure function of the proton from its asymptotic value is shown to be within 15-20 percent. Data for the resonance energy region at Q{sup 2}<3 GeV{sup 2} are used to obtain integrals of the polarization structure functions of the nucleon in the region x=0.45-1, where no experimental data are available. These integrals reveal scaling behavior at Q{sup 2}=2-3 GeV{sup 2}, and their values agree withmore » those obtained by extrapolating experimental data to the high-x region. 23 refs., 2 figs.« less
  • This dissertation presents results of experiment E94-010 performed at Jefferson Laboratory (simply known as JLab) in Hall A. The experiment aimed to measure the low Q 2 evolution of the Gerasimov-Drell-Hearn (GDH) integral from Q 2 = 0.1 to 0.9 GeV 2. The GDH sum rule at the real photon point provides an important test of Quantum Chromodynamics (QCD). The low Q 2 evolution of the GDH integral contests various resonance models, Chiral Perturbation Theory ({chi} PT) and lattice QCD calculations, but more importantly, it helps us understand the transition between partonic and hadronic degrees of freedom. At high Qmore » 2, beyond 1 GeV 2, the difference of the GDH integrals for the proton and the neutron is related to the Bjorken sum rule, another fundamental test of QCD. In addition, results of the measurements for the spin structure functions g 1 and g 2, cross sections, and asymmetries are presented. E94-010 was the first experiment of its kind at JLab. It used a high-pressure, polarized 3He target with a gas pressure of 10 atm and average target polarization of 35%. For the first time, the polarized electron source delivered an average beam polarization of 70% with a beam current of 15 micro A. The limit on the beam current was only imposed by the target. The experiment required six different beam energies from 0.86 to 5.1 GeV. This was the first time the accelerator ever reached 5.1 GeV. Both High-Resolution Spectrometers of Hall A, used in singles mode, were positioned at 15.5 ┬░ each.« less
  • We show that the data of Aubert et al. on the structure function of iron is in apparent violation of the energy-momentum sum rule. The systematics of the finite-q/sup 2/ corrections, when compared to data of Arnold et al., are an important ingredient to the argument. The discrepancy can be removed by an approximately 5% renormalization of the data of Aubert et al.
  • I discuss in this talk the physics of the Q{sup 2} dependence of the G{sub l}(x,Q{sup 2}) structure function sum rule. For Q{sup 2} > 3 GeV{sup 2}, the Q{sup 2} variation is controlled by pure QCD radiative corrections. For 0.5 < Q{sup 2} < 3 GeV{sup 2}, the twist-four contribution becomes significant, but stays perturbative. For Q{sup 2} below {approximately} 0.05, the sum rule is determined by low-energy theorems. The rapid change of the sum rule between 0.05 and 0.5 GeV{sup 2} signals the transition between parton and hadron degrees of freedom.