The challenge of the EMC effect: existing data and future directions

Since the discovery that the ratio of inclusive charged lepton (per-nucleon) cross-sections from a nucleus A to the deuteron is not unity — even in deep inelastic scattering kinematics — a great deal of experimental and theoretical effort has gone into understanding the phenomenon. The EMC effect, as it is now known, shows that even in the most extreme kinematic conditions the effects of the nucleon being bound in a nucleus cannot be ignored. In this paper, we collect the most precise data available for various nuclear to deuteron ratios, as well as provide a commentary on the current status of the theoretical understanding of this thirty year old effect. (author)