Measurements of the Q2-Dependence of the Proton and Deuteron Spin Structure Functions g1p and g1d

TL;DR

This study measures the Q2-dependence of proton and deuteron spin structure functions g1p and g1d over a range of x and Q2, finding no significant Q2 dependence at high Q2 and noting a decrease at lower Q2, with results consistent with the Bjorken sum rule.

Contribution

It provides new measurements of g1/F1 over a broad kinematic range and analyzes their Q2 dependence, offering insights into spin structure functions and sum rules.

Findings

g1/F1 is consistent with no Q2-dependence at high Q2

g1/F1 decreases at lower Q2

Results support the Bjorken sum rule but show Delta_q less than quark-parton model expectations

Abstract

The ratio g1/F1 has been measured over the range 0.03<x<0.6 and 0.3<Q2<10 (GeV/c)2 using deep-inelastic scattering of polarized electrons from polarized protons and deuterons. We find g1/F1 to be consistent with no Q2-dependence at fixed x in the deep-inelastic region Q^2>1 (GeV/c)2. A trend is observed for g1/F1 to decrease at lower Q2. Fits to world data with and without a possible Q2-dependence in g1/F1 are in agreement with the Bjorken sum rule, but Delta_q is substantially less than the quark-parton model expectation.