P. Kessler et S. Ong, PSEUDOSCALAR-MESON PRODUCTION IN GAMMA-ASTERISK-GAMMA-ASTERISK COLLISIONS, Physical review. D. Particles and fields, 48(7), 1993, pp. 2974-2977
We show that pseudoscalar-meson production by two off-shell photons ca
n be used to check the Brodsky-Lepage model for two-photon exclusive c
hannels in QCD versus the vector-dominance model. The behavior of the
form factor of the Mgammagamma* vertex is indeed quite different in e
ither model.