The Small $x$ Behavior of $g_1$ in the Resummed Approach

Abstract

The double logarithmic terms ${\alpha }_s{\ln }^{2}x$ are important to predict precisely the small $x$ behavior of the spin structure function $g_1$. We numerically analyze the evolution of the flavor non-singlet $g_1$ including the all-order resummed effect of these terms. It is pointed out that the next-to-leading logarithmic corrections produce an unexpectedly large suppression factor over the experimentally accessible range of $x$ and $Q^2$. This implies that the next-to-leading logarithmic contributions are very important in order to obtain a definite prediction.

Comments: 9 pages, ps figures included, sprocl.sty, psfig.sty, and here.sty are required. Invited talk presented at the International Symposium on ``QCD Corrections and New Physics'' October 27-29, 1997 Hiroshima, Japan