Rho production with polarized photons

Abstract The process γ + P → P + ϱ 0 → P + π + + π - has been studied with polarized photons between 2.0 and 2.5 GeV. Decay pions and recoil proton were detected with a wire plane system. We find a strong preference for ϱ 0 -decay parallel to the polarization vector, expressed by the ratiom σ ⊥ / σ | = 0.17 ± 0.07, which indicates the predominance of diffractive rho production.