Running coupling effects for the singlet structure function g_1 at small x

Abstract

The running of the QCD coupling is incorporated into the infrared evolution equations for the flavour structure function g_1. The explicit expressions for g_1 including the total resummation of the double-logarithmic contributions and accounting for the running coupling are obtained. We predict that asymptotically g_1 ~ x^{- \Delta_S}, with the intercept \Delta_S = 0.86, which is more than twice larger than the non-singlet intercept. The impact of the initial quark (\delta q) and gluon (\delta g) densities on the sign of g_1 at x << 1 is discussed and explicit expressions relating \delta q and \delta g are obtained.

Comments: The sign of g_1 at small x is discussed in more details, 3 refs are added