Q2 dependence of the spin structure function in the resonance region.

Abstract

In this paper, we show what we can learn from the CEBAF experiments on spin-structure functions, and the transition from the Drell-Hearn-Gerasimov sum rule in the real photon limit to the spin-dependent sum rules in deep inelastic scattering, and how the asymmetry ${\mathit{A}}_{1}$(x,${\mathit{Q}}^{2}$) approaches the scaling limit in the resonance region. The spin structure function in the resonance region alone cannot determine the spin-dependent sum rule due to the kinematic restriction of the resonance region. The integral ${\mathcal{F}}_{0}^{1}${${\mathit{A}}_{1}$(x,${\mathit{Q}}^{2}$)${\mathit{F}}_{2}$(x,${\mathit{Q}}^{2}$)/2x[1+R(x,${\mathit{Q}}^{2}$)]}dx is estimated from ${\mathit{Q}}^{2}$=0--2.5 ${\mathrm{GeV}}^{2}$. The result shows that there is a region where both contributions from the baryon resonances and the deep inelastic scattering are important; thus it provides important information on the high twist effects on the spin-dependent sum rule.