The role of three-body collisions in phi meson production processes near threshold

The amplitude of subthreshold phi meson production is calculated using dominant tree-level diagrams for three-body collisions. It is shown that the production can overwhelmingly be described by two-step processes. The effect of the genuine three-body contribution (i.e., the contribution which cannot be factorized) is discussed. The production rate of phi mesons resulting from these processes is presented for proton induced reactions on carbon