Unified description of the non-singlet spin dependent structure function $g_1$ incorporating Altarelli-Parisi evolution and the double logarithmic $l{n}^2(1/x)$ effects at low $x$

Abstract

A unified equation for the non-singlet spin dependent structure function $g_1^{ns}(x,Q^2)$ which incorporates the complete leading order Altarelli-Parisi evolution at finite $x$ and double logarithmic $l{n}^2(1/x)$ effects at $x\to 0$ is formulated. The solution of this equation reasonably agrees with the recent data obtained by the Spin Muon Collaboration.

10 pages, plain LATEX, 3 eps figures. Corrected: several misprints and a calculation error leading to negligible changes in fig. 2 and 3. To appear in Phys. Lett. B