Spin-Flavor Decomposition in Polarized Semi-Inclusive Deep Inelastic Scattering Experiments at Jefferson Lab

A Jefferson Lab experiment proposal was discussed in this talk. The experiment is designed to measure the beam-target double-spin asymmetries $A_{1n}^h$ in semi-inclusive deep-inelastic $\vec n({\vec e}, e^\prime \pi^+)X$ and $\vec n({\vec e}, e^\prime \pi^-)X$ reactions on a longitudinally polarized $^3$He target. In addition to $A_{1n}^h$, the flavor non-singlet combination $A_{1n}^{\pi^+ - \pi^-}$, in which the gluons do not contribute, will be determined with high precision to extract $\Delta d_v(x)$ independent of the knowledge of the fragmentation functions. The data will also impose strong constraints on quark and gluon polarizations through a global NLO QCD fit.