  Measurements involving the gluon spin density, Delta G=G++ - G+-, can play an
important role in the quantitative understanding of proton structure. To
demonstrate this, we show that the shape of the gluon asymmetry, A(x,t)=Delta
G(x,t)/G(x,t), contains significant dynamical information about
non-perturbative spin-orbit effects. It is instructive to use a separation
A(x,t)=A_0^epsilon(x)+epsilon(x,t), where A_0^epsilon(x) is an approximately
scale-invariant form that can be calculated within a given factorization
prescription from the measured distributions Delta q(x,t), q(x,t) and G(x,t).
Applying this separation with the J_z=1/2 sum rule provides a convenient way to
determine the total amount of orbital angular momentum generated by mechanisms
associated with confinement and chiral dynamics. The results are consistent
with alternate non-perturbative approaches to the determination of orbital
angular momentum in the proton. Our studies help to specify the accuracy that
future measurements should achieve to constrain theoretical models for nucleon
structure.
