φphotoproduction near threshold with Okubo-Zweig-Iizuka evadingφNNinteractions

Abstract

Existing intermediate and high energy $\ensuremath{\varphi}$-photoproduction data is consistent with purely diffractive production (i.e., Pomeron exchange). However, near threshold $(1.574 \mathrm{GeV}l{E}_{\ensuremath{\gamma}}^{\mathrm{lab}}l~2.0 \mathrm{GeV})$ the energy dependence of the diffractive amplitude is not well known and nondiffractive amplitudes such as ${\ensuremath{\pi}}^{0}$ and $\ensuremath{\eta}$ exchange, $s\overline{s}$ knockout, and nonzero $\ensuremath{\varphi}\mathrm{NN}$ couplings can give sizable contributions to the cross section and polarization density matrix elements of the $\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\varphi}}{K}^{+}{K}^{\ensuremath{-}}$ decay angular distribution. We stress the importance of measurements with linearly polarized photons near the $\ensuremath{\varphi}$ threshold to separate natural and unnatural parity exchange mechanisms. Approved and planned $\ensuremath{\varphi}$ photoproduction and electroproduction experiments at Jefferson Lab will help establish the relative dynamical contributions near threshold and clarify outstanding theoretical issues related to apparent Okubo-Zweig-Iizuka violations.