Study of photoproduction of vector mesons on deuterium by 5.5 GeV linearly polarized photons

The experimental results of a deuterium bubble chamber photoproduction study of half a million pictures at 5.5 GeV are presented. This experiment was performed using a monoenergetic and linearly polarized photon beam facility at SLAC. At 5.5 GeV the beam polarization is greater than 90 percent, and the average FWHM of the beam energy spectrum is 0.6 GeV. The reaction γd → π+π-d was studied in detail. A clear sample of γd → rho0d channel was obtained, and using the rho0 decay distribution in terms of an extended density matrix which includes correlation with the beam polarization, one could determine nine independent density matrix parameters. The study of rho0 production and decay in the reaction channel γd → rho0d was found to proceed almost completely through natural parity exchanges; the contribution from unnatural parity exchanges being only (5.3 +- 4.5) percent for momentum transfer paralleltparallel less than or equal to 0.25 GeV2. It was observed that the rho0 production mechanism conserves s-channel cms helicity for paralleltparallel less than or equal to 0.15 GeV2. After carrying out the fitting to the π+π- mass distribution, one obtained for the rho0 mass and width the values (766 +- 5) and (139 +- 11) MeV, respectively. The rho0 production cross section in this channel was determined to be (9.1 +- 0.8) μb. The final states π+π-π0d, K+K-d, π+π+π-π-d, and π+π-π-pp were obtained for the production of ω, phi, rho', and A1 mesons, respectively. However, due to insufficient statistics, no conclusive remarks could be made. (U.S.)