On the determination of the multipoles in pion photo-production by polarized photons

Abstract

Although the multipole transition amplitude of pion photoproduction process in the vicinity of the first pion-nucleon resonance is well-known, nothing definite can be said as yet about the angular momentum state responsible for the higher resonances. It is pointed out in this note that photo-production experiments with polarized photons and in particular, the determination of the polarization of the recoil proton from an unpolarized target, the differential cross-section from a polarized target and the polarization of the recoil proton from a polarized target will be particularly useful for this purpose. Expressions which can be experimentally tested are given for these quantities assuming the dominance of various multipoles.