Spin structure function g1(x,Q) and the DHGHY integral I(Q) at low Q: predictions from the GVMD model

Theoretical predictions for the polarized nucleon structure function g1(x,Q2) at low Q2 are obtained in the framework of the generalized vector meson dominance model. Contributions from both light and heavy vector mesons are evaluated. In the photoproduction limit the first moment of g1 is related to the static properties of the nucleon via the Drell-Hearn-Gerasimov-Hosoda-Yamamoto sum rule. This property is employed to fix the magnitude of the light vector meson contribution to g1, using the recent measurements in the region of baryonic resonances. The results are compared to the data on g1(x,Q2). Finally, the DHGHY moment function I(Q2) is calculated, and our theoretical predictions are confronted with the recent preliminary data obtained at the Jefferson Laboratory. (orig.)