Spin asymmetries of semi-inclusive cross sections for the production of positively and negatively charged hadrons have been measured in deep-inelastic scattering of polarized positrons on polarized hydrogen and He targets, in the kinematic range 0.023 < x < 0.6 and 1 GeV2 < Q2 < 10 GeV2. Polarized quark distributions are extracted as a function of x for up (u + ū) and down (d + d̄) flavors. The up quark polarization is positive and the down quark polarization is negative in the measured range. The polarization of the sea is compatible with zero. The first moments of the polarized quark distributions are presented. The isospin non-singlet combination Δq3 is consistent with the prediction based on the Bjorken sum rule. The moments of the polarized quark distributions are compared to predictions based on SU(3)f flavor symmetry and to a prediction from lattice QCD.
|Number of pages||12|
|Journal||Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics|
|State||Published - 1999|
Bibliographical noteFunding Information:
We gratefully acknowledge the DESY management for its support and the DESY staff and the staffs of the collaborating institutions. This work was supported by the FWO-Flanders, Belgium; the Natural Sciences and Engineering Research Council of Canada; the INTAS, HCM, and TMR network contributions from the European Community; the German Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie; the Deutscher Akademischer Austauschdienst (DAAD); the Italian Istituto Nazionale di Fisica Nucleare (INFN); Monbusho, JSPS, and Toray Science Foundation of Japan; the Dutch Foundation for Fundamenteel Onderzoek der Materie (FOM); the UK Particle Physics and Astronomy Research Council; and the US Department of Energy and National Science Foundation.
ASJC Scopus subject areas
- Nuclear and High Energy Physics