Transversity and the Polarized Drell-Yan Process in $p\bar{p}\to {\mu }^{+}{\mu }^{-}X$

Estimates are given for the double spin asymmetry in lepton-pair production from collisions of transversely polarized protons and antiprotons for the kinematics of the recently proposed PAX experiment at GSI on the basis of predictions for the transversity distribution from the probabilistic quark-parton model developed earlier.