New results on spin and 3D structure measurements
The nucleon spin structure has puzzled the physics community for about 30 years since the original discovery made by the EMC collaboration in late 1980s that the quark spin only contributes a small fraction to the nucleon spin. With major efforts from both theoretical and experimental sides, the quark spin contribution is relatively well known and the gluon spin contribution is becoming known in recent years. To fully understand the nucleon spin structure, the study has gone beyond one dimensional to three dimensional (3D) to probe the confined motion and access the orbital angular momentum of the partons inside the nucleon. In this paper, we briefly review the experimental status and the progress during the last year on the study of nucleon spin and 3D structures.
