Polarised Deep Inelastic Muon-Proton Scattering at 200 Gev/c.
Available from UMI in association with The British Library. Results are presented for the spin dependent asymmetry parameter A_1 and the structure function g_1 measured in deep inelastic scattering of polarised muons from a polarised ammonia target. The asymmetry has been extracted from data taken at an incident beam energy of 200 GeV and cover the kinematic range of Bjorken scaling variable x from 0.02 to 0.5 and four-momentum transfer squared, Q^2 from 3 to ~eq60 (GeV/C) ^2. Thus these data greatly extend the kinematic region studied by the experiments performed at SLAC using an electron beam. The asymmetry A_1 is evaluated as a function of x-Bjorken and Q^2 and is compared to the SLAC data. It is concluded that there is no evidence for scaling violations and that at high x the EMC data are consistent with the SLAC results. At low-x however, the new asymmetry tends to be smaller than predictions from the extrapolation of the 0.94 surdx fit to the SLAC data to the low-x region. The integral of g_1(x) in the interval 0 < x < 1 is evaluated and is compared to the predictions of the Bjorken and Ellis-Jaffe sum-rules. It is found that _0int^1g_1(x) dx = 0.11 +/- 0.03 which is two standard deviations lower than the value of 0.174 predicted by the Ellis-Jaffe sum-rule.
- Pub Date:
- Physics: Elementary Particles and High Energy