TNT Colloquium: Orbital Angular Momentum, Wandzura-Wilczek relations, and Generalized Transverse Momentum Distributions [Duke]

Wandzura Wilczek relations between matrix-elements of bilocal operators on the
light cone allow us to access the color forces among quarks and gluons
from off-forward scattering processes. I will present an analysis of the parton
transverse momentum, $k_T$, substructure of these processes
involving Generalized Parton Distributions (GPDs). I will focus, in particular,
on three helicity configurations that can be detected analyzing specific spin
asymmetries: two correspond to longitudinal proton polarization and are
associated with quark orbital angular momentum and spin-orbit correlations; the
third, obtained for transverse proton polarization, is a generalization of the
relation obeyed by the g2 structure function from inclusive polarized
scattering. An additional relation connecting the off-forward extension of the
Sivers function to an off-forward quark-gluon-quark term, known as
the Qiu-Sterman term, will also be discussed.