The protons and neutrons--the basic form of baryonic matter--are complex bound states of QCD quarks and gluons which are challenging to describe in simple terms. Much of what we know about them is learned through precision electromagnetic probes, and the results are best depicted in terms of partons in the so-called infinite momentum frame. A significant breakthrough in recent years has been the realization that partons can be probed in both spatial and momentum spaces simultaneously, yielding a tomographic picture in quantum-phase space. In this talk, progress and prospects in exploring the partonic picture of the nucleon, its mass and spin structure in particular, are discussed.

ANL Physics Division Colloquium Schedule