Virtual photon asymmetry for confined, interacting Dirac particles with spin symmetry

Departement fu¨r Physik und Astronomie, Universit¨at Basel, Switzerland(Dated: February 4, 2008)We study the Bjorken x dependence of the virtual photon spin asymmetry in polarized deepinelastic scattering of electrons from hadrons. We use an exactly solved relativistic potential modelof thehadron, treating the constituentsas independentmassless Dirac particles boundto an infinitelymassive force center. The potential is chosen to have spin symmetry and a linear radial dependencewith spherical symmetry. The effect of interactions of the struck constituent with the remainderof the target on the longitudinal photon asymmetry is demonstrated. In particular, the small-x suppression of the photon asymmetry observed in polarized deep inelastic scattering from theproton is shown to be a consequence of these interactions. The effect of p–wave components ofthe Dirac wave function, long known to give an important contribution to the spin of hadrons, isexplicitly demonstrated through their interference with the s–wave term.