Photoproduction of charmed particles and asymptotically free field theories

It is argued that photoproduction of charmed particles can be considered within the same theoretical framework as deep inelastic scattering off the usual hadrons. The role of large Q² now plays the charmed quark mass m_c². In particular, the standard technique of the moments from the structure functions is applicable. In this way we get a sum rule which relates an integral from the charmed particles photoproduction cross section to the heavy quark mass and effective coupling constant of strong interactions.