POLARIZATION OBSERVABLES IN VECTOR-MESON PHOTOPRODUCTION

The photoproduction of vector mesons (rho, omega, phi) is of renewed i nterest because intense high energy beams of polarized electrons and p hotons are under development. These beams and also polarized targets m ake it possible to explore the dynamics of basic baryon structure. As a step toward that goal, an analysis of all possible polarization obse rvables for the case of vector meson photoproduction from a nucleon ta rget is presented. The question of which observables are needed to det ermine completely the basic photoproduction amplitudes and the relatio nships between spin observables are addressed. Such theorems are most readily demonstrated by representing all observables as bilinear produ cts of helicity amplitudes and using known properties of Dirac gamma a nd spin-1 matrices. The general angular dependence of spin observables , especially near thresholds and resonances, is examined for the vecto r meson case. The criteria for a complete set of observables and the r elationships between observables are then presented.