Search

We use a generalization of the Rosenbluth separation method for a model independent simultaneous extraction of the Compton Form Factors H and E , from virtual Compton scattering data on an unpolarized target. A precise evaluation of H and E , enabled by the proposed method, is the first step towards pinning down the distribution of angular momentum inside the proton. [ABSTRACT FROM AUTHOR]

Abstract: 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 with orbital angular momentum are related to the target-spin asymmetry in deeply virtual Compton scattering, already measured at HERMES. [Copyright &y& Elsevier]