Coherent photoproduction of vector mesons on deuterium at 5.5 GeV

Abstract

Coherent photoproduction of vector mesons ${\ensuremath{\rho}}^{0}$, $\ensuremath{\omega}$, $\ensuremath{\varphi}$, and ${\ensuremath{\rho}}^{\ensuremath{'}}$ on deuterium was studied using the SLAC 82-in. bubble chamber exposed to linearly polarized photons at 5.5 GeV. The reaction channel $\ensuremath{\gamma}d\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}d$ was studied in detail. Nine independent density-matrix parameters have been determined from the ${\ensuremath{\rho}}^{0}$ decay distribution. $\ensuremath{\rho}$ production in this channel was found to proceed almost completely through natural-parity exchange for $|t|\ensuremath{\le}0.25$ Ge${\mathrm{V}}^{2}$ and conserve $s$-channel c.m. helicity for $|t|\ensuremath{\le}0.15$ Ge${\mathrm{V}}^{2}$. A measurement of differential cross section for this channel has been made.