Sivers Differential Cross Section for $\pi+X$ Production via $p^{\uparrow}+p$ Collisions, and the Quark Sivers Function.

We recently estimated pion+X production via proton collisions with a polarized proton target to enable the Collins fragmentation function to be determined via future experiments. In the present article we first estimate the Silvers differential cross section obtianed from experiments with the target proton having both positive and negative polarizations, and then estimate the Sivers Function using quark distribution functions.