QCD is believed to be the correct theory of the strong interaction, however, color confinement prevents direct observation of color-charged particles. The strong interaction also generates 98% of the mass of the visible universe, yet, the details of confinement remain mysterious.

Deep inelastic electron scattering (DIS) on unpolarized and longitudinally polarized nucleons has provided important information on the distributions of the asymptotically-free non-interacting quarks in the nucleon and nuclei. These parton distributions encode all the non-perturbative information of the confined system and serve as a theoretically rigorous starting point to begin to unravel the phenomena of confinement.

With a transversely polarized target, polarized electron DIS experiments provide a unique opportunity to understand the quark-gluon correlations existing in nuclear matter. This talk will emphasize the importance of these experiments in extracting the next-to-leading twist matrix elements which are proportional to an average color Lorentz force felt by the struck quark. The results from two recent polarized DIS experiments using transversely polarized targets will be presented along with a discussion of future experiments at JLab and an electron ion collider.

Argonne Physics Division Seminar Schedule