Photoproduction and Forbidden Decays ofϕMesons

Abstract

Photoproduction of $\varphi$ mesons from hydrogen and carbon was studied at 5.2 GeV by observing $\varphi \to K^{+}{K}^{-}$ decays. The results show that $\varphi$'s are produced diffractively with a $\varphi$-nucleon cross section ${\sigma }_{\varphi N}={9.8}_{-3.3\mathrm{}}^{+2.9\mathrm{}}$ mb. In addition, 80 000 pion pairs were measured to search for the $G$-parity-nonconserving decay $\varphi \to {\pi }^{+}{\pi }^{-}$. Assuming complete interference between $\rho \to {\pi }^{+}{\pi }^{-}$ and $\varphi \to {\pi }^{+}{\pi }^{-}$, we found an upper limit of $\frac{{\Gamma }_{\varphi \to 2\pi }}{{\Gamma }_{\varphi \to \mathrm{all}}}=2.7\mathrm{}\times {10}^{-4}$ at the 95% level.