Fixed-t subtracted dispersion relations are presented for Compton scattering off the nucleon at energies E γ ≤ 500 MeV, as a formalism to extract the nucleon polariz-abilities with a minimum of model dependence. The scalar polarizability difference α − β and the backward spin polarizability γ π enter directly as fit parameters in this formalism. Compton scattering off the nucleon is determined ...
