Transversity distributions and Drell-Yan spin asymmetries

We discuss transversity distributions and Drell-Yan transverse double spin asymmetries. First, the antiquark flavor asymmetry Delta(T)(u) over bar/Del ta(T)(d) over bar is discussed by using two different descriptions, a meson -cloud model and a Pauli exclusion model. We find that both calculations pr oduce a significant Delta(T)(d) over bar excess over Delta(T)(u) over bar. Next, we study its effects on the transverse spin asymmetry A(TT) and on th e Drell-Yan proton-deuteron asymmetry Delta(T)sigma(pd)/2 Delta(T)sigma(pp) We find that the ratio Delta(T)sigma(pd)/2 Delta(T)sigma(pp) is very usefu l for investigating the flavor asymmetry effect.