Hosted by: Oleg Eyser

Recent advances in theory have shown that it is possible to directly calculate the canonical quark and gluon orbital angular momentum contributions to the proton spin in lattice QCD. When boosted to the infinite momentum frame, the quark and gluon orbital angular momentum operators defined in the gauge-invariant nucleon spin sum rule of X. S. Chen et al. are the same as those derived from generalized transverse momentum distributions. The latter reduce to the canonical orbital angular momenta in the light-cone gauge, and can be measured in high-energy scattering experiments. I will show that these orbital angular momentum operators can be defined locally, and discuss the strategies of calculating their matrix elements in lattice QCD.