Spin duality in the nucleon: Measurements at Jefferson Lab Hall A

The Bloom-Gilman duality has been experimentally demonstrated for spin independent structure functions. Duality is observed when the smooth scaling curve at high momentum transfer is an average over the resonance bumps at lower momentum transfer, but at the same value of scaling variable x. Signs of quark-hadron duality for the spin Dependant structure function g 1 of the proton has been recently reported by the Hermes collaboration and the Jefferson lab Hall B collaboration. Jefferson Lab experiment 01 -012 used the polarized He-3 target in Hall A for a precision extraction of the neutron spin structure function g(1)(n) and the virtual photon asymmetry A(1)(n) in the resonance region up to Q(2) = 4(GeV/c)(2). Data from E01-012 combined with Deep-Inelastic-Scattering data will provide a precision test of quark-hadron duality predictions for neutron spin structure functions. This will be one of the first precision tests of spin and flavor dependence of quark-hadron duality. The demonstration of duality for spin structure functions will enable the use of resonance data to study the nucleon spin structure in the very high x region.