Effects Of The Quantity $\sigma_{TS}$ On The Spin Structure Functions Of   Nucleons In The Resonance Region
  In this paper, we investigate the effects of the quantity $\sigma_{TS}$ on the spin-structure functions of nucleons in the resonance region. The Schwinger sum rule for the spin structure function $g_2(x,Q^2)$ at the real photon limit is derived for the nucleon treated as a composite system, and it provides a crucial constraint on the longitudinal transition operator which has not been treated consistently in the literature. The longitudinal amplitude $S_{\frac 12}$ is evaluated in the quark model with the transition operator that generates the Schwinger sum rule. The numerical results of the quantity $\sigma_{TS}$ are presented for both spin structure functions $g_1(x,Q^2)$ and $g_2(x,Q^2)$ in the resonance region. Our results show that this quantity   plays an important role in the low $Q^2$ region, which can be tested in the future experiments at CEBAF. 
Zhenping Li and Dong Yubing