Phenomenology of g_1(x) in the Observed Small-x Region

Abstract

We examine the behaviour of the polarised structure function data for g_1(x) in the region of small x (~0.01 to 0.1) for the various available targets (proton, neutron and deuteron) with the aim of clarifying what may be safely deduced with regard to the relation of the currently attained small-x region and the asymptotic behaviour as x -> 0. We find that fits using a single power-like term are susceptible to the isospin combination used. Double-power fits are more stable and also provide some evidence for an underlying SU(2) symmetry of the structure functions.