Quark-antiquark asymmetry of helicity distributions in the nucleon sea

We study the helicity distributions of light flavor quark-antiquark (q (q) over bar) pairs in the nucleon sea. The valence quarks are handled by adopting the light-cone SU(6) quark-spectator-diquark model and the sea q (q) over bar pairs are treated from statistical consideration by introducing the helicity suppression factors l(q)(x) and (l) over bar (q)(x) to parametrize the helicity distributions of q-flavor sea quark and antiquark respectively, while Delta l(q)(x) = l(q)(x) - (l) over bar (q)(x) represents a combined effect of helicity contribution due to sea q (q) over bar pairs. From fitting the nucleon polarization asymmetries A(1)(N) in inclusive deep inelastic scattering processes and the single-spin asymmetries A(L)(W +/-) in Drell-Yan type processes, we find a significant asymmetry between the quark and antiquark helicity distributions of the nucleon sea. Therefore the quark-antiquark asymmetry of helicity distributions of nucleon sea q q (q) over bar pairs, i.e., Delta q(s)(x) not equal Delta(q) over bar (s)(x), plays an important role for a comprehensive understanding of the nucleon spin content.