We show that pseudoscalar-meson production by two off-shell photons can be used to check the Brodsky-Lepage model for two-photon exclusive channels in QCD versus the vector-dominance model. The behavior of the form factor of the $M{\gamma }^{*}{\gamma }^{*}$ vertex is indeed quite different in either model.

• Received 25 May 1993

DOI:https://doi.org/10.1103/PhysRevD.48.R2974