Double Transverse Spin Asymmetries at Next-to-leading Order in QCD

We present a technique to calculate the cross sections and spin asymmetries for transversely polarized $pp$ collisions at NLO in QCD and report on the use of this technique for the processes $p^{\uparrow} p^{\uparrow} \to \gamma X$, $p^{\uparrow} p^{\uparrow} \to \pi X$ and $p^{\uparrow} p^{\uparrow} \to l^+ l^- X$.