K. Ackerstaff et al., Flavor decomposition of the polarized quark distributions in the nucleon from inclusive and semi-inclusive deep-inelastic scattering, PHYS LETT B, 464(1-2), 1999, pp. 123-134
Spin asymmetries of semi-inclusive cross sections for the production of pos
itively and negatively charged hadrons have been measured in deep-inelastic
scattering of polarized positrons on polarized hydrogen and He-3 targets,
in the kinematic range 0.023 < x < 0.6 and 1 GeV2 < Q(2) < 10 GeV2. Polariz
ed quark distributions are extracted as a function of x for up (u + (u) ove
r bar) and down (d + (d) over bar) flavors. The up quark polarization is po
sitive and the down quark polarization is negative in the measured range. T
he polarization of the sea is compatible with zero. The first moments of th
e polarized quark distributions are presented. The isospin non-singlet comb
ination dq, is consistent with the prediction based on the Bjorken sum rule
. The moments of the polarized quark distributions are compared to predicti
ons based on SU(3)(f) flavor symmetry and to a prediction from lattice QCD.
(C) 1999 Published by Elsevier Science B.V. All rights reserved.