Helicity Amplitudes and Sum Rules for Real and Virtual Photons
  Results of the recently developed unitary isobar model (MAID) are presented for helicity amplitudes, spin asymmetries, structure functions and relevant sum rules for real and virtual photons in the resonance region. Our evaluation of the energy-weighted integrals is in good agreement for the proton but shows big discrepancies for the neutron. 
Lothar Tiator (Universitaet Mainz)