Photoproduction of nucleon resonances and nucleon spin structure function in the resonance region

The photoproduction of nucleon resonances is calculated based on a chiral constituent quark model including both relativistic corrections ${H}_{\mathrm{rel}}$ and two-body exchange currents, and it is shown that these effects play an important role. We also calculate the first moment of the nucleon spin structure function ${g}_{1}{(x,Q}^{2})$ in the resonance region, and obtain a sign-changing point around ${Q}^{2}\ensuremath{\sim}0.27 {\mathrm{GeV}}^{2}$ for the proton.