Proton Spin Structure in the Resonance Region

Abstract

We have examined the spin structure of the proton in the region of the nucleon resonances ($1.085\text{ }\text{ }\mathrm{GeV}<W<1.910\text{ }\text{ }\mathrm{GeV}$) at an average four momentum transfer of ${Q}^{2}=1.3\text{ }\text{ }{\mathrm{GeV}}^{2}$. Using the Jefferson Lab polarized electron beam, a spectrometer, and a polarized solid target, we measured the asymmetries ${A}_{\ensuremath{\parallel}}$ and ${A}_{\ensuremath{\perp}}$ to high precision, and extracted the asymmetries ${A}_{1}$ and ${A}_{2}$, and the spin structure functions ${g}_{1}$ and ${g}_{2}$. We found a notably nonzero ${A}_{\ensuremath{\perp}}$, significant contributions from higher-twist effects, and only weak support for polarized quark-hadron duality.