Phenomenological Determination of the OrbitalAngular Momentum

摘要

Measurements involving the gluon spin, ΔG(x, t) and the corresponding asymmetry, A(x,t) = ΔG(x,t)/ G(x,t) play an important role in quantitative understanding of proton structure. We have modeled the asymmetry perturbatively and calculated model corrections to obtain informa-tion about non-perturbative spin-orbit effects. These models are consistent with existing COMPASS and HERMES data on the gluon asymmetry. The J_z = 1/2 sum rule is used to generate values of orbital angular momentum at LO and NLO. For models consistent with data, the orbital angular momentum is small. Our studies specify accuracy that future measurements should achieve to constrain theoretical models for nucleon structure.