Estimating cross sections for the production of new particles

Methods are discussed for estimating the cross section for the associated production of charmed particle in photon-hadron or hadron-hadron collisions. Charm is here assumed to be the new quantum number carried by the constituents of the psi(3095) and psi(3684). Expressions are proposed for the relation of the charmed quark distribution function to that of the strange quark and for the production of charmed pairs in pp collisions. The values proposed are not the result of a single model calculation but occur if simple interpretations of existing data or some measure of theoretical consistency are required. (U.K.)