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

TL;DR

This paper investigates the behaviour of the polarized structure function g_1(x) at small x, analyzing data for different targets to understand its asymptotic properties and underlying symmetries.

Contribution

It provides a comparative analysis of power-law fits to g_1(x) data, revealing the stability of double-power fits and evidence for SU(2) symmetry.

Findings

Double-power fits are more stable than single-power fits.

Evidence suggests an underlying SU(2) symmetry in g_1(x).

The isospin combination affects the fit susceptibility.

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.