We have measured the spin-dependent structure function g1 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 GeV2 < Q2 < 60 GeV2. Its first moment, ∫0 1 g1 p(x)dx, is found to be 0.136±0.011 (stat.)± 0.011 (syst.) at Q2 = 10GeV2. 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.
ASJC Scopus subject areas
- Nuclear and High Energy Physics