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Title: Quark Helicity Distributions at Large Longitudinal Momentum Fraction

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Stanford Linear Accelerator Center (SLAC)
Sponsoring Org.:
USDOE
OSTI Identifier:
907719
Report Number(s):
SLAC-PUB-12503
Journal ID: ISSN 0556-2821; PRVDAQ; arXiv:0705.1553; TRN: US0703526
DOE Contract Number:
AC02-76SF00515
Resource Type:
Journal Article
Resource Relation:
Journal Name: Phys.Rev.Lett.99:082001,2007
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; HELICITY; LONGITUDINAL MOMENTUM; MAGNETIC MOMENTS; NUCLEONS; ORBITAL ANGULAR MOMENTUM; QUARKS; VALENCE; Phenomenology-HEP, Theory-HEP,HEPPH, HEPTH

Citation Formats

Avakian, Harut, /Jefferson Lab, Brodsky, Stanley J., /SLAC, Deur, Alexandre, /Jefferson Lab, Yuan, Feng, and /RIKEN BNL. Quark Helicity Distributions at Large Longitudinal Momentum Fraction. United States: N. p., 2007. Web.
Avakian, Harut, /Jefferson Lab, Brodsky, Stanley J., /SLAC, Deur, Alexandre, /Jefferson Lab, Yuan, Feng, & /RIKEN BNL. Quark Helicity Distributions at Large Longitudinal Momentum Fraction. United States.
Avakian, Harut, /Jefferson Lab, Brodsky, Stanley J., /SLAC, Deur, Alexandre, /Jefferson Lab, Yuan, Feng, and /RIKEN BNL. Mon . "Quark Helicity Distributions at Large Longitudinal Momentum Fraction". United States. doi:. https://www.osti.gov/servlets/purl/907719.
@article{osti_907719,
title = {Quark Helicity Distributions at Large Longitudinal Momentum Fraction},
author = {Avakian, Harut and /Jefferson Lab and Brodsky, Stanley J. and /SLAC and Deur, Alexandre and /Jefferson Lab and Yuan, Feng and /RIKEN BNL},
abstractNote = {},
doi = {},
journal = {Phys.Rev.Lett.99:082001,2007},
number = ,
volume = ,
place = {United States},
year = {Mon May 14 00:00:00 EDT 2007},
month = {Mon May 14 00:00:00 EDT 2007}
}
  • We study the quark helicity distributions at largemore » $x$ in perturbative QCD, taking into account contributions from the valence Fock states of the nucleon which have nonzero orbital angular momentum. These states are necessary to have a nonzero anomalous magnetic moment. We find that the quark orbital angular momentum contributes a large logarithm to the negative helicity quark distribution in addition to its power behavior, scaling as $$(1-x)^5\log^2(1-x)$$ in the limit of $$x\to 1$$. Our analysis show that the ratio of the polarized over unpolarized down quark distributions, $$\Delta d/d$$, will still approach 1 in this limit. By comparing with the current experimental data, we find that this ratio will cross zero at $$x\approx 0.75$$.« less
  • We study the quark helicity distributions at large x in perturbative QCD, taking into account contributions from the valence Fock states of the nucleon which have nonzero orbital angular momentum. These states are necessary to have a nonzero anomalous magnetic moment. We find that the quark orbital angular momentum contributes a large logarithm to the negative helicity quark distributions in addition to its power behavior, scaling as (1-x)^5\log^2(1-x) in the limit of x\to 1. Our analysis shows that the ratio of the polarized over unpolarized down quark distributions, \Delta d/d, will still approach 1 in this limit. By comparing withmore » the experimental data, we find that this ratio should cross zero at x\approx 0.75.« less
  • Within the LO QCD parton model of Semi-Inclusive Deep Inelastic Scattering, lN{yields}lhX, with unintegrated quark distribution and fragmentation functions, we study the P{sub hT} dependence of the double longitudinal-spin asymmetry A{sub LL}. We include 1/Q kinematic corrections, which induce an azimuthal modulation of the asymmetry, analogous to the Cahn effect in unpolarized SIDIS. We show that a study of A{sub LL} and of the weighted DSA A{sub LL}{sup cos{phi}{sub h}} allows to extract the transverse momentum dependence of the unintegrated helicity distribution function g{sub 1L}{sup q}(x,k{sub perpendicular}) [or {delta}q(x,k{sub perpendicular})]. Predictions, based on some models for the unknown functions, aremore » given for ongoing COMPASS, HERMES and JLab experiments.« less
  • We study the quark helicity distributions at large x in perturbative QCD, taking into account contributions from the valence Fock states of the nucleon which have nonzero orbital angular momentum. We find that the quark orbital angular momentum contributes a large logarithm to the negative helicity quark distributions in addition to its power behavior, scaling as (1-x){sup 5}log{sup 2}(1-x) in the limit of x{yields}1. Our analysis shows that the ratio of the polarized over unpolarized down quark distributions, {delta}d/d, will still approach 1 in this limit. By comparing with the experimental data, we find that this ratio should cross zeromore » at x{approx_equal}0.75.« less
  • Longitudinal and transverse parton distributions for pion and nucleon are calculated from hadron vertexes obtained by a study of form factors within relativistic quark models. The relevance of the one-gluon-exchange dominance at short range for the behavior of the form factors at large momentum transfer and of the parton distributions at the end points is stressed.