Precision Measurement of the Proton Spin Structure Function gp1
K. Abe, T. Akagi, P. L. Anthony, R. Antonov, R. G. Arnold, T. Averett, H. R. Band, J. M. Bauer, H. Borel, P. E. Bosted, V. Breton, J. Button-Shaferhttp://academic.research.microsoft.com/io.ashx?type=5&id=19208115&selfId1=0&selfId2=0&maxNumber=12&query=
We have measured the ratio gp1/Fp1 over the range 0.029<x<0.8 and 1.3<Q2<10 (GeV/c)2 using deep-inelastic scattering of polarized electrons from polarized ammonia. An evaluation of the integral 1gp1\(x,Q2\) dx at fixed Q2 = 3 (GeV/c)2 yields 0.127+/-0.004\(stat\)+/-0.010\(syst\), in agreement with previous experiments, but well below the Ellis-Jaffe sum rule prediction of 0.160+/-0.006. In the quark-parton model, this implies Deltaq = 0.27+/-0.10.