Electroproduction ofρandϕMesons

Abstract

We report measurements of ${\ensuremath{\rho}}^{0}$ and $\ensuremath{\phi}$ electroproduction at 19.5 GeV in a wide-aperture spectrometer which detected the scattered electron and the decay products of the vector mesons. As $|{q}^{2}|$ increases, the $\ensuremath{\rho}$ mass spectrum shape changes, the momentum-transfer distribution broadens, and the ratio of the $\ensuremath{\rho}$ cross section to the total cross section decreases. The ratio of longitudinally to transversely polarized ${\ensuremath{\rho}}^{0}$ mesons is ${0.45}_{\ensuremath{-}0.10}^{+0.15}$ at $|{q}^{2}|=m{\ensuremath{\rho}}^{2}$, and the interference between longitudinal and transverse amplitudes is almost maximal. The relative $\ensuremath{\phi}$-meson cross section also decreases as $|{q}^{2}|$ increases.