COHERENT PHOTOPRODUCTION OF ¿-MESONS OFF PROTONS AT THRESHOLD ENERGIES

Observables from vector meson photoproduction by linearly-polarized photons can be expressed in term of bilinear combinations of helicity amplitudes parameterized by the Spin Density Matrix Elements (SDMEs). These SDMEs give straightforward relations for understanding the nature of the parity exchange at threshold energies, as well as for extracting signatures of the Okubo-Zweig-Iizuka violation. Measurement of SDMEs for ¿p ¿ ¿p in the photon energy range of 1.7 to 1.9 GeV(momentum transfer squared t range of ¿1.2 to ¿0.25 GeV2 ) and 1.9 to 2.1 GeV (t range of ¿1.4 to ¿0.25 GeV2 ) from the g8b experimental data collected in the summer of 2005 in the Hall B of Jefferson Lab are reported herein.