Fig. 1

The recent result from E99-117 on Aⁿ₁, plotted with world data taken with polarized ³He targets, shows for the first time that the Aⁿ₁ asymmetry becomes positive at large Bjorken x as predicted by the constituent quark model (yellow band) and perturbative QCD fits (shades of blue). The best fit of the data is the parameterization shown in red, for which hadron helicity conservation is broken, suggesting, along with the constituent quark model, that the orbital angular momentum of quarks is important in this region (Zheng et al. 2004).

Back to article