The photon structure and exclusive production of vector mesons in $\gamma\gamma$ collisions

Abstract.

The process of exclusive vector meson production, $\gamma\gamma \to J/\psi \rho^0$, is studied for almost real photons. This process may be reduced to the photoproduction of $J/\psi$ off the $\rho^0$ meson. We discuss the possibility of extracting the gluon distribution of $\rho^0$ and of the photon from such a measurement. Predictions are also given for the reaction $e^+ e^- \to e^+ e^- J/\psi \rho^0$ for various $e^+e^-$ cms energies typical for LEP and for the future linear colliders.