The Gluon Spin Asymmetry as a Link to ΔG and Orbital Angular Momentum

The fundamental program in high energy spin physics focuses on the spin structure of the nucleon. The gluon and orbital angular momentum components of the nucleon spin are virtually unknown. The J_z = {1 / 2} sum rule involves the integrated parton densities and can be used to extract information on the orbital angular momentum and its evolution. To avoid any bias on a model of ΔG, we assume that the gluon asymmetry A = ΔG/G can be used to extract ΔG over a reasonable kinematic region. Combining the results for ΔG with the evolution equations, we can determine a theoretical expression for the orbital angular momentum and its evolution.