  We argue that due to Parity constraints, the helicity combination of the
purely momentum space counterparts of the Wigner distributions -- the
generalized transverse momentum distributions -- that describes the
configuration of an unpolarized quark in a longitudinally polarized nucleon,
can enter the deeply virtual Compton scattering amplitude only through matrix
elements involving a final state interaction. The relevant matrix elements in
turn involve light cone operators projections in the transverse direction, or
they appear in the deeply virtual Compton scattering amplitude at twist three.
Orbital angular momentum or the spin structure of the nucleon was a major
reason for these various distributions and amplitudes to have been introduced.
We show that the twist three contributions associated to orbital angular
momentum %to deeply virtual Compton scattering provide observables related to
orbital angular momentum and are related to the target-spin asymmetry in deeply
virtual Compton scattering, already measured at HERMES.

High Energy Physics - Phenomenology