The Production of Heavy Mesons

Using Fermi's theory of multiple production, the production of heavy mesons in a nucleon-nucleon collision (with primary energy $<20M{c}^2$) is studied. One obtains the result that heavy mesons should be produced singly about 10 times more frequently than in pairs. Creation of mesons in a meson-nucleon collision is also considered, and it is found that mesons of energy $E<M{c}^2$ would, most likely, pass through nuclear matter without further creation of mesons, while for $E>\mathrm{}2M{c}^2$ the probability of multiplication is large. In a qualitative way, the results deduced seem to agree rather well with experiments.