Production of a charmed-meson pair in photon-photon interaction

The cross section for the exclusive production of a pair of charmed mesons in photon-photon interaction is calculated on the basis of the constituent model. The resulting predictions are compared with the predictions of heavy-quark effective theory. It is shown that the light valence quark of the D meson plays a significant role not only in hadronization but also in the process leading to the production of a heavy c quark. Moreover, it is shown that, because of the strong interaction of a primary photon field with the charge of a light quark, a similar situation persists even in the limit m(Q)-->infinity, whence it follows that the application of heavy-quark effective theory to the case of photon--photon interaction is incorrect, since one of the dominant mechanisms of the production of heavy mesons is disregarded in this case. (C) 2004 MAIK "Nauka/Interperiodica".