Flavor asymmetry of polarized antiquark distributions and semi-inclusive DIS

Abstract

The $1/N_c$ –expansion of QCD suggests large flavor asymmetries of the polarized antiquark distributions in the nucleon. This is confirmed by model calculations in the large– $N_c$ limit (chiral quark–soliton model), which give sizable results for $\Delta\bar u(x) - \Delta\bar d (x)$ and $\Delta\bar u(x) + \Delta\bar d (x) - 2 \Delta \bar s (x)$ . We compute the contributions of these flavor asymmetries to the spin asymmetries in hadron production in semi-inclusive deep–inelastic scattering. We show that the large flavor asymmetries predicted by the chiral quark–soliton model are consistent with the recent HERMES data for spin asymmetries in charged hadron production.