Double transverse-spin asymmetries in Drell--Yan and $J\mathrm{/}\psi$ production from proton--antiproton collisions

We perform a NLO numerical study of the double transverse-spin asymmetries in the $J\mathrm{/}\psi$ resonance region for proton–antiproton collisions. We analyze the large $x$ kinematic region, relevant for the proposed PAX experiment at GSI, and discuss the implication of the results for the extraction of the transversity densities.