Measurement of the Spin-Dependent Structure Function $g_1(x)$ of the Proton

Abstract

We have measured the spin-dependent structure function $g_1^p$ of the proton in deep inelastic scattering of polarized muons off polarized protons, in the kinematic range $0.003<x<0.7$ and $1\text{mbox}{GeV}^2<Q^2<60\text{mbox}{GeV}^2$. Its first moment, ${\int }_0^1{g}_1^p(x)dx$, is found to be $0.136\pm 0.011(\text{mbox}stat.)\pm 0.011(\text{mbox}syst.)$ at $Q^2=10\text{mbox}{GeV}^2$. This value is smaller than the prediction of the Ellis--Jaffe sum rule by two standard deviations, and is consistent with previous measurements. A combined analysis of all available proton, deuteron and neutron data confirms the Bjorken sum rule to within $10\%$ of the theoretical value.

Comments: 11 pages, CERN-PPE/94-57