Near-threshold meson production in pp collisions

A program of near threshold investigations of meson production channels in polarized(p) + p collisions has been carried out by the DISTO collaboration. Preliminary results are given. The ability of the experimental apparatus to eventually determine total and differential cross-sections is demonstrated. A number a spin observables will also be evaluated. The potentialities of these measurements for the understanding of two leading problems in meson physics: OZI rule violation in φ production and status of the η' meson, are discussed. (author)