SPIN STRUCTURE OF THE NUCLEON AND ASPECTS OF DUALITY

In a quantitative analysis of the neutron spin structure first moment in terms of its "twist expansion", the size of higher twists (twist-4) is found to be surprisingly small at Q²= 1 GeV² lending support to the concept of "global duality". The value of d₂ at Q²= 1 GeV² tends to suggest significant higher than twist-3 contribution (twist-5 and beyond). More precision data in the range 1 ≤ Q² ≤ 5 GeV² are needed for a definitive conclusion since the lattice prediction are at odds with the measured data at Q² = 4.8 GeV².