Photoproduction ofρ0andρ−mesons at 3 GeV

Abstract

The photoproduction of ${\ensuremath{\rho}}^{0}$ and ${\ensuremath{\rho}}^{\ensuremath{-}}$ mesons has been studied at 3 GeV in the reactions $\ensuremath{\gamma}d\ensuremath{\rightarrow}d{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}^{\ensuremath{-}}$, $\ensuremath{\gamma}d\ensuremath{\rightarrow}{p}_{s}n{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, and $\ensuremath{\gamma}d\ensuremath{\rightarrow}{p}_{s}p{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}$. For ${\ensuremath{\rho}}^{0}$ and ${\ensuremath{\rho}}^{\ensuremath{-}}$ production in these reactions we present the total and differential cross sections, the decay angular distributions, and the spin density matrix elements. The photoproduction of the ${\ensuremath{\rho}}^{0}$ is found to be consistent with $s$-channel helicity conservation and is dominated by natural-parity exchange. The ${\ensuremath{\rho}}^{\ensuremath{-}}$ meson production has approximately equal natural- and unnatural-parity-exchange contributions. The unnatural-parity-exchange contribution is consistent with one-pion exchange and is used to estimate the value of ${\ensuremath{\Gamma}}_{\ensuremath{\rho}\ensuremath{\pi}\ensuremath{\gamma}}$.