Inspired by recent measurements with the CLAS detector at Jefferson Lab, we perform a self-consistent analysis of world data on the proton structure function $g_1$ in the range $0.17<Q^2<30(\mathrm{G}\mathrm{e}\mathrm{V}/c{)}^2$. We compute for the first time low-order moments of $g_1$ and study their evolution from small to large values of $Q^2$. The analysis includes the latest data on both the unpolarized inclusive cross sections and the ratio $R={\sigma }_L/{\sigma }_T$ from Jefferson Lab, as well as a new model for the transverse asymmetry $A_2$ in the resonance region. The contributions of both leading and higher twists are extracted, taking into account effects from radiative corrections beyond the next-to-leading order by means of soft-gluon resummation techniques. The leading twist is determined with remarkably good accuracy and is compared with the predictions obtained using various polarized parton distribution sets available in the literature. The contribution of higher twists to the $g_1$ moments is found to be significantly larger than in the case of the unpolarized structure function $F_2$.

• Received 23 December 2004

DOI:https://doi.org/10.1103/PhysRevD.71.054007