/ Experiment-HEP hep-ex/0209018

Evidence for quark hadron duality in the proton spin asymmetry A(1)

Airapetian, A. ; Akopov, N. ; Akopov, Z. ; Amarian, M. ; Ammosov, V.V. ; Aschenauer, E.C. ; Avakian, H. ; Avakian, R. ; Avetissian, A. ; Avetissian, E. ; Bailey, P. ; Baturin, V. ; Baumgarten, C. ; Beckmann, M. ; Belostotski, S. ; Bernreuther, S. ; Bianchi, N. ; Blok, H.P. ; Bottcher, H. ; Borissov, A. ; Bouhali, O. ; Bouwhuis, M. ; Brack, J. ; Brauksiepe, S. ; Brull, A.

Published in: Phys.Rev.Lett.
Year: 2003
Vol.: 90
Page No: 092002
Pages: 5

Abstract: Spin-dependent lepton-nucleon scattering data have been used to investigate the validity of the concept of quark-hadron duality for the spin asymmetry $A_1$. Longitudinally polarised positrons were scattered off a longitudinally polarised hydrogen target for values of $Q^2$ between 1.2 and 12 GeV$^2$ and values of $W^2$ between 1 and 4 GeV$^2$. The average double-spin asymmetry in the nucleon resonance region is found to agree with that measured in deep-inelastic scattering at the same values of the Bjorken scaling variable $x$. This finding implies that the description of $A_1$ in terms of quark degrees of freedom is valid also in the nucleon resonance region for values of $Q^2$ above 1.6 GeV$^2$.

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