STAR Spin Working Group 

Unraveling the quark and gluon substructure of nucleons and nuclei is one of the major goals in nuclear physics today. A great deal has been learned about the partonic structure of the nucleon at leading twist and with collinear factorization, but much is still unknown. Furthermore, new avenues have been opened during the past decade to explore the nucleon structure beyond leading twist and collinear factorization. The ability to collide polarized beams at RHIC provides unique information regarding these issues.

                                 - STAR Decadal Plan (2010)