NLO QCD procedure of the semi-inclusive deep inelastic scattering data analysis with respect to the light quark polarized sea

The semi-inclusive deep inelastic scattering (SIDIS) process is considered. A theoretical procedure is proposed allowing the direct extraction from the SIDIS data of the first moments of the polarized valence distributions and of the first moment difference of the light sea quark polarized distributions in the next to leading QCD order. The validity of the procedure is confirmed by the respective simulations.

Figure 1

$N^{{\pi }^{+}}$ and $N^{{\pi }^{-}}$ obtained with PEPSI for neutron target. The dashed and solid lines correspond to ${\pi }^{+}$, and ${\pi }^{-}$ productions, respectively.

Figure 2

$N^{{\pi }^{+}}$ and $N^{{\pi }^{-}}$ obtained with PEPSI for proton target. The dashed and solid lines correspond to ${\pi }^{+}$, and ${\pi }^{-}$ productions, respectively.

Figure 3

$N^{{\pi }^{+}}$ and $N^{{\pi }^{-}}$ obtained with PEPSI for deutron target. The dashed and solid lines correspond to ${\pi }^{+}$, and ${\pi }^{-}$ productions, respectively.

Figure 4

Ratios of $N^{{\pi }^{+}}\equiv N_{\uparrow \downarrow }^{{\pi }^{+}}+N_{\uparrow \uparrow }^{{\pi }^{+}}$ and $N^{{\pi }^{-}}\equiv N_{\uparrow \downarrow }^{{\pi }^{-}}+N_{\uparrow \uparrow }^{{\pi }^{-}}$ obtained with the polarized event generator PEPSI for the different targets. The picture is in good agreement with the respective EMC result (Fig. 10 in Ref. 14.)

Figure 5

Simulated (squares) and theoretical pion difference asymmetries for proton and deutron targets. The solid lines correspond to the theoretical asymmetries obtained from Eq. (3) with GRSV2000LO (broken sea) parametrizations for the valence distributions.

Figure 6

The reconstructed polarized valence distributions (squares). The solid lines correspond to the respective GRSV2000LO (broken sea) parametrizations.

Figure 7

Polarized valence distributions given by the different parametrizations with the symmetric and weakly broken sea. Solid lines correspond to the purely symmetric parametrizations from Refs. 16, 22, while the dashed line corresponds to parametrization FS2000 [set ($\mathrm{i}-$) in Ref. 10 ] with a weakly broken sea. All of these parametrizations demonstrate quite similar behavior.