Exclusive production of heavy flavours in the pp system near meson thresholds

Abstract

We investigate the production of heavy vector mesons with ss̄, cc̄ and bb̄ contents. Starting from a factorization of the full transition amplitude into a hard production amplitude and soft initial and final state interactions, we employ the exchange of three gluons or an instanton 4q qq̄ interaction for the production mechanism. The structure of the mesons produced and the interacting protons are formulated as constituent qq̄ or quark–scalar diquark systems in a covariant relativistic quark model. As an upper limit, we find a typical suppression of the total threshold charm and bottom cross section relative to ϕ(1020) production by typically two and five orders of magnitude, respectively; the proper inclusion of effects from Lorentz contraction and the deformation of the interacting proton turns out to be of significant importance.