Approaches to threshold meson production
  Near-threshold data on meson production in nucleon-nucleon scattering are analysed in the short-range limit which permits a quantitative comparison of the production in two and three-body final states. The relative strengths of different meson productions are broadly in line with the predictions of one-meson-exchange models and it is deviations from these which are indications of extra physics. 
Colin Wilkin