DAPNIA-07-288 |
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Quark-Hadron Duality in Spni Structure Function g1p and g1d |
P.E. Bosted et al (R. De Masi, M. Garçon, F.X. Girod, J.M. Laget, L. Morand, S.A. Morrow, F. Sabatié) |
New measurements of the spin structure functions of the proton and deuteron g1p(x,Q2) and g1d(x,Q2) in the nucleon resonance region are compared with extrapolations of target-mass corrected next-to-leading-order (NLO) QCD fits to higher energy data. Averaged over the entire resonance region (W < 2 GeV), the data and QCD fits are in good agreement in both magnitude and Q2 dependence for Q2 > 1.7 GeV2/c2. This “global” duality appears to result from cancellations among the prominent “local” resonance regions: in particular strong sigma3/2 contributions in the Delta(1232) region appear to be compensated by strong sigma1/2 contributions in the resonance region centered on 1.5 GeV. These results are encouraging for the extension of NLO QCD fits to lower W and Q2 than have been used previously. |