Author/Authors :
Spin Muon Collaboration (SMC)، نويسنده , , B. Adeva، نويسنده , , E. Arik، نويسنده , , A. Arvidson، نويسنده , , B. Badelek، نويسنده , , G. Bardin، نويسنده , , G. Baum، نويسنده , , P. Berglund، نويسنده , , L. Betev، نويسنده , , R. Birsa، نويسنده , , N. de Botton، نويسنده , , F. Bradamante، نويسنده , , A. Bravar، نويسنده , , Rodrigo A. Bressan، نويسنده , , S. Bultmann، نويسنده , , E. Burtin، نويسنده , , D. Crabb، نويسنده , , J. Cranshaw، نويسنده , , T. Cuhadar، نويسنده , , S. Dalla Torre-Colautti، نويسنده , , et al.، نويسنده ,
Abstract :
We present a new measurement of the virtual photon proton asymmetry A1p from deep inelastic scattering of polarized muons on polarized protons in the kinematic range 0.0008 < x < 0.7 and 0.2 < Q2 < 100 GeV2. With this, the statistical uncertainty of our measurement has improved by a factor of 2 compared to our previous measurements. The spin-dependent structure function g1p is determined for the data with Q2 > 1 GeV2. A perturbative QCD evolution in next-to-leading order is used to determine g1p(x) at a constant Q2. At Q2 = 10 GeV2 we find, in the measured range, ∫0.0030.7g1P(x)dx=0.139±0.006 (stat) ±0.008 (syst) ±0.006(evol). The value of the first moment Г1P= ∫01g1p(x)d x of g1p depends on the approach used to describe the behaviour of g1p at low x. We find that the Ellis-Jaffe sum rule is violated. With our published result for Γ1d we confirm the Bjorken sum rule with an accuracy of ≈ 15% at the one standard deviation level.
