Compton scattering by the nucleon

The status of Compton scattering by the nucleon at energies of the first and second resonance is summarized. In addition to a general test of dispersion theories and a precise determination of polarizabilities, the validities of four fundamental sum rules are explored. Recommended   averages of experimental values for the electromagnetic polarizabilities and spin-polarizabilities of the nucleon are determined: αp=12.0±0.6αp=12.0±0.6, βp=1.9∓0.6βp=1.9∓0.6, αn=12.5±1.7αn=12.5±1.7, βn=2.7∓1.8βn=2.7∓1.8 (unit 10-4fm3), γπ(p)=-38.7±1.8, γπ(n)=58.6±4.0 (unit 10-4fm4).