SAGA-HE-176-01, TMU-NT-01-04 Polarized light-antiquark distributions in a meson-cloud model

Flavor asymmetry is investigated in polarized light-antiquark distributions by a meson-cloud model. In particular, ρ meson contributions to ∆ū−∆d̄ are calculated. We point out that the g2 part of ρ contributes to the structure function g1 of the proton in addition to the ordinary longitudinally polarized distributions in ρ. This kind of contribution becomes important at medium x (> 0.2) with small Q (∼1 GeV). Including N → ρN and N → ρ∆ splitting processes, we obtain the polarized ρ effects on the light-antiquark flavor asymmetry in the proton. The results show ∆d̄ excess over ∆ū, which is very different from some theoretical predictions. Our model could be tested by experiments in the near future.