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Evidence for Quark-Hadron Duality in the Proton Spin Asymmetry $A_1$

HERMES Collaboration·A. Airapetian
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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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HERMES Collaboration, A. Airapetian. 2003-02-04. Evidence for Quark-Hadron Duality in the Proton Spin Asymmetry $A_1$. https://doi.org/10.1103/physrevlett.90.092002

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