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 γ0(p)=-0.58±0.20 and γ0(n)=+0.38±0.22 in units of 10-4 fm4 where the different signs are found to be due to the isospin dependencies of the E0+ and the (M,E)1+(1/2) amplitudes. The backward spin-polarizabilities are predicted to be γπ(p)=-36.6 and γπ(n)=+58.3, to be compared with the experimental values γπ(p)=-36.4±1.5 and γπ(n)=+58.6±4.0. 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.