Structure of the nucleon and spin-polarizabilities

Spin-polarizabilities are predicted by calculating the cross-section difference σ3/2−σ1/2 from available data for the resonance couplings A3/2 and A1/2 and CGLN amplitudes. The forward spin-polarizabilities are predicted to be and in units of 10−4fm4 where the different signs are found to be due to the isospin dependencies of the E0+ and the amplitudes. The backward spin-polarizabilities are predicted to be and , to be compared with the experimental values and . Electric γE and magnetic γM spin-polarizabilities are introduced and discussed in terms of the E1 and M1/E2 components of the photo-absorption cross section of the nucleon.