Transversity distributions and Drell-Yan spin asymmetries

We discuss transversity distributions and Drell-Yan transverse double spin asymmetries. First, the antiquark flavor asymmetry ∆ T ¯ u/∆ T ¯ d is discussed by using two different descriptions, a meson-cloud model and a Pauli exclusion model. We find that both calculations produce a significant ∆ T ¯ d excess over ∆ T ¯ u. Next, we study its effects on the transverse spin asymmetry A T T and on the Drell-Yan proton-deuteron asymmetry ∆ T σ pd /2∆ T σ pp. We find that the ratio ∆ T σ pd /2∆ T σ pp is very useful for investigating the flavor asymmetry effect.